437 lines
7.6 KiB
C
437 lines
7.6 KiB
C
#include <u.h>
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#include <libc.h>
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#include <draw.h>
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#include "sudoku.h"
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int allowbits[Brdsize] = {
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0x00100,
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0x00200,
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0x00400,
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0x00800,
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0x01000,
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0x02000,
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0x04000,
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0x08000,
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0x10000
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};
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int boxind[Brdsize][Brdsize] = {
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{0,1,2,9,10,11,18,19,20},
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{3,4,5,12,13,14,21,22,23},
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{6,7,8,15,16,17,24,25,26},
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{27,28,29,36,37,38,45,46,47},
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{30,31,32,39,40,41,48,49,50},
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{33,34,35,42,43,44,51,52,53},
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{54,55,56,63,64,65,72,73,74},
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{57,58,59,66,67,68,75,76,77},
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{60,61,62,69,70,71,78,79,80},
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};
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int colind[Brdsize][Brdsize] = {
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{0,9,18,27,36,45,54,63,72},
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{1,10,19,28,37,46,55,64,73},
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{2,11,20,29,38,47,56,65,74},
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{3,12,21,30,39,48,57,66,75},
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{4,13,22,31,40,49,58,67,76},
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{5,14,23,32,41,50,59,68,77},
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{6,15,24,33,42,51,60,69,78},
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{7,16,25,34,43,52,61,70,79},
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{8,17,26,35,44,53,62,71,80},
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};
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int rowind[Brdsize][Brdsize] = {
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{0,1,2,3,4,5,6,7,8},
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{9,10,11,12,13,14,15,16,17},
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{18,19,20,21,22,23,24,25,26},
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{27,28,29,30,31,32,33,34,35},
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{36,37,38,39,40,41,42,43,44},
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{45,46,47,48,49,50,51,52,53},
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{54,55,56,57,58,59,60,61,62},
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{63,64,65,66,67,68,69,70,71},
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{72,73,74,75,76,77,78,79,80},
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};
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static int maxlevel;
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static int solved;
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void
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printbrd(int *board)
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{
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int i;
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for(i = 0; i < Psize; i++) {
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if(i > 0 && i % Brdsize == 0)
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print("\n");
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print("%2.2d ", board[i] & Digit);
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}
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print("\n");
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}
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int
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getrow(int cell)
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{
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return cell/9;
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}
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int
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getcol(int cell)
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{
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return cell%9;
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}
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int
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getbox(int cell)
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{
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int row = getrow(cell);
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int col = getcol(cell);
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return 3*(row/3)+ col/3;
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}
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void
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setdigit(int cc, int num)
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{
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board[cc] = (board[cc] & ~Digit) | num;
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}
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int
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boxcheck(int *board)
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{
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int i,j,d,sum,last,last2;
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for (i = 0; i < 9; i++) {
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for (d = 0;d < 9; d++) {
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sum=0;
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last=-1;
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last2=-1;
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for (j = 0; j < 9; j++) {
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if (board[boxind[i][j]] & allowbits[d]) {
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sum++;
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last2=last;
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last=boxind[i][j];
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} else
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sum += ((board[boxind[i][j]] & Solve)==(d << 4)) ? 1: 0;
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}
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if (sum==0)
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return(0);
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if ((sum==1)&&(last>=0))
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if (!setallowed(board,last,d))
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return(0);
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if((sum == 2) && (last >= 0) && ( last2 >= 0) &&
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(getrow(last) == getrow(last2))) {
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for (j = 0; j < 9; j++) {
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int c = rowind[getrow(last)][j];
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if ((c != last)&&(c != last2)) {
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if (board[c] & allowbits[d]) {
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board[c] &= ~allowbits[d];
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if ((board[c] & Allow)==0)
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return(0);
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}
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}
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}
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}
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if((sum == 2) && (last >= 0) && (last2 >= 0) &&
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(getcol(last) == getcol(last2))) {
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for (j = 0;j <9;j++) {
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int c = colind[getcol(last)][j];
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if ((c != last) && (c != last2)) {
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if (board[c] & allowbits[d]) {
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board[c] &= ~allowbits[d];
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if ((board[c] & Allow) == 0)
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return(0);
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}
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}
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}
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}
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}
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}
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return(1);
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}
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int
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rowcheck(int *board)
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{
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int i,j,d,sum,last;
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for (i = 0; i < 9; i++) {
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for (d = 0; d < 9; d++) {
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sum = 0;
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last = -1;
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for (j = 0; j <9 ; j++) {
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if (board[rowind[i][j]] & allowbits[d]) {
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sum++;
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last = j;
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} else
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sum += ((board[rowind[i][j]] & Solve) == (d << 4)) ? 1: 0;
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}
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if (sum == 0)
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return(0);
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if ((sum == 1) && (last >= 0)) {
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if (!setallowed(board, rowind[i][last], d))
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return(0);
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}
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}
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}
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return(1);
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}
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int
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colcheck(int *board)
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{
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int i,j,d,sum,last;
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for (i = 0; i < 9; i++) {
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for (d = 0; d < 9; d++) {
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sum = 0;
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last = -1;
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for (j = 0;j < 9;j++) {
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if (board[colind[i][j]] & allowbits[d]) {
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sum++;
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last = j;
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} else
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sum += ((board[colind[i][j]] & Solve) == (d << 4)) ? 1: 0;
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}
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if (sum == 0)
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return(0);
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if ((sum == 1) && (last >= 0)) {
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if (!setallowed(board, colind[i][last], d))
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return(0);
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}
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}
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}
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return(1);
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}
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int
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setallowed(int *board, int cc, int num)
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{
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int j, d;
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int row, col, box;
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board[cc] &= ~Allow;
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board[cc] = (board[cc] & ~Solve) | (num << 4);
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row = getrow(cc);
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for (j = 0; j < 9; j++) {
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if (board[rowind[row][j]] & allowbits[num]) {
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board[rowind[row][j]] &= ~allowbits[num];
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if ((board[rowind[row][j]] & Allow) == 0)
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return(0);
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}
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}
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col = getcol(cc);
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for (j = 0; j < 9; j++) {
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if (board[colind[col][j]] & allowbits[num]) {
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board[colind[col][j]] &= ~allowbits[num];
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if ((board[colind[col][j]] & Allow) == 0)
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return(0);
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}
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}
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box = getbox(cc);
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for (j = 0;j < 9;j++) {
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if (board[boxind[box][j]] & allowbits[num]) {
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board[boxind[box][j]] &= ~allowbits[num];
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if ((board[boxind[box][j]] & Allow)==0)
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return(0);
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}
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}
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for (j = 0;j < 81; j++)
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for (d = 0; d < 9; d++)
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if ((board[j] & Allow) == allowbits[d])
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if (!setallowed(board, j, d))
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return(0);
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if (!boxcheck(board)||!rowcheck(board)||!colcheck(board))
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return(0);
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for (j = 0; j < 81; j++)
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for (d = 0; d < 9; d++)
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if ((board[j] & Allow) == allowbits[d])
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if (!setallowed(board, j, d))
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return(0);
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return(1);
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}
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int
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chksolved(int *board)
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{
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int i;
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for (i = 0; i < Psize; i++)
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if ((board[i] & Allow) != 0)
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return 0;
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solved = 1;
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return solved;
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}
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int
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findmove(int *board)
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{
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int i, d;
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int s;
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s = nrand(Psize);
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for (i=(s+1)%81;i!=s;i=(i+1)%81) {
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if (!(board[i] & Allow)) {
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d=(board[i] & Solve) >> 4;
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if ((board[i] & Digit)!=d)
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return(i);
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}
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}
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return(-1);
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}
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void
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attempt(int *pboard, int level)
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{
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int tb[Psize];
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int i, j, k;
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int s, e;
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if (level > maxlevel)
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maxlevel = level;
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if (level > 25)
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exits("level"); /* too much */
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s = nrand(Psize);
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for (i = (s + 1) % Psize; i != s; i = (i + 1) % Psize) {
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if ((pboard[i] & Allow) != 0) {
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e=nrand(9);
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for (j = (e + 1) % 9; j != e; j = (j + 1) % 9) {
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if (pboard[i] & allowbits[j]) {
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for (k = 0; k < Psize; k++)
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tb[k] = pboard[k];
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if (setallowed(tb, i, j)) {
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tb[i] = (tb[i] & ~Digit) | j;
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if (chksolved(tb)) {
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for (k = 0;k < Psize; k++)
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pboard[k] = tb[k];
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return; /* bad! */
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}
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attempt(tb, level + 1);
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if (chksolved(tb)) {
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for (k = 0; k < Psize; k++)
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pboard[k] = tb[k];
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return;
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}
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tb[i] |= Digit;
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if (level > 25)
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return;
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}
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}
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}
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}
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}
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}
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void
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solve(void)
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{
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int pboard[Psize];
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int i, c;
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if (!solved) {
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for (i = 0; i < Psize; i++)
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pboard[i] = Allow | Solve | Digit;
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for (i = 0; i < Psize; i++) {
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c = board[i] & Digit;
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if ((0 <= c) && (c < 9)) {
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if (!setallowed(pboard,i,c)) {
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print("starting position impossible... failed at cell %d char: %d\n", i, c + 1);
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return;
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}
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}
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}
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attempt(pboard,0);
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for (i = 0; i < Psize; i++)
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board[i] = (board[i] & ~Solve) | (pboard[i] & Solve);
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}
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}
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int
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checklegal(int cc, int d)
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{
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int hold = board[cc];
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int j, row, col, box;
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board[cc] |= Digit;
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row = getrow(cc);
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for (j = 0; j < Brdsize; j++)
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if ((board[rowind[row][j]] & Digit) == d) {
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board[cc] = hold;
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return(0);
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}
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col = getcol(cc);
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for (j = 0; j < Brdsize; j++)
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if ((board[colind[col][j]] & Digit) == d) {
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board[cc] = hold;
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return(0);
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}
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box = getbox(cc);
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for (j = 0; j < Brdsize; j++)
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if ((board[boxind[box][j]] & Digit) == d) {
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board[cc] = hold;
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return(0);
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}
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board[cc]=hold;
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return(1);
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}
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void
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clearp(void)
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{
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int i;
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for(i = 0; i < Psize; i++) {
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board[i] = (Allow | Solve | Digit);
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}
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solved = 0;
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}
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void
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makep(void)
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{
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int i,d;
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do {
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clearp();
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maxlevel=0;
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for (d = 0; d < Brdsize; d++) {
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i = nrand(Psize);
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if (board[i] & allowbits[d]) {
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setallowed(board, i, d);
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board[i] = (board[i] & ~Digit) | d;
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}
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}
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attempt(board, 0);
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for (i = 0; i < Psize; i++) {
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if ((0 <= (board[i] & Digit)) && ((board[i] & Digit) < 9))
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board[i] |= MLock;
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setdigit(i, board[i] & Digit);
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}
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if (!solved) {
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fprint(2, "failed to make puzzle\n");
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exits("failed to make puzzle");
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}
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} while (!solved);
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}
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