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PriorityQueue: add bulk insertion methods

master
John Schmidt 2019-02-26 20:44:27 +01:00 committed by Andrew Kelley
parent cddc77dd97
commit dd34c21779
1 changed files with 59 additions and 21 deletions
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80
std/priority_queue.zig
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@ -28,7 +28,10 @@ pub fn PriorityQueue(comptime T: type) type {
pub fn add(self: *Self, elem: T) !void {
try ensureCapacity(self, self.len + 1);
addUnchecked(self, elem);
}
fn addUnchecked(self: *Self, elem: T) void {
self.items[self.len] = elem;
var child_index = self.len;
while (child_index > 0) {
@ -45,6 +48,13 @@ pub fn PriorityQueue(comptime T: type) type {
self.len += 1;
}
pub fn addSlice(self: *Self, items: []const T) !void {
try self.ensureCapacity(self.len + items.len);
for (items) |e| {
self.addUnchecked(e);
}
}
pub fn peek(self: *Self) ?T {
return if (self.len > 0) self.items[0] else null;
}
@ -58,7 +68,7 @@ pub fn PriorityQueue(comptime T: type) type {
const last = self.items[self.len - 1];
self.items[0] = last;
self.len -= 1;
siftDown(self);
siftDown(self, 0);
return first;
}
@ -70,8 +80,8 @@ pub fn PriorityQueue(comptime T: type) type {
return self.items.len;
}
fn siftDown(self: *Self) void {
var index: usize = 0;
fn siftDown(self: *Self, start_index: usize) void {
var index = start_index;
const half = self.len >> 1;
while (true) {
var left_index = (index << 1) + 1;
@ -106,6 +116,24 @@ pub fn PriorityQueue(comptime T: type) type {
}
}
/// PriorityQueue takes ownership of the passed in slice. The slice must have been
/// allocated with `allocator`.
/// Deinitialize with `deinit`.
pub fn fromOwnedSlice(allocator: *Allocator, compareFn: fn (a: T, b: T) bool, items: []T) Self {
var queue = Self{
.items = items,
.len = items.len,
.allocator = allocator,
.compareFn = compareFn,
};
const half = (queue.len >> 1) - 1;
var i: usize = 0;
while (i <= half) : (i += 1) {
queue.siftDown(half - i);
}
return queue;
}
pub fn ensureCapacity(self: *Self, new_capacity: usize) !void {
var better_capacity = self.capacity();
if (better_capacity >= new_capacity) return;
@ -252,24 +280,34 @@ test "std.PriorityQueue: sift up with odd indices" {
try queue.add(e);
}
expectEqual(u32(1), queue.remove());
expectEqual(u32(2), queue.remove());
expectEqual(u32(5), queue.remove());
expectEqual(u32(6), queue.remove());
expectEqual(u32(7), queue.remove());
expectEqual(u32(7), queue.remove());
expectEqual(u32(11), queue.remove());
expectEqual(u32(12), queue.remove());
expectEqual(u32(13), queue.remove());
expectEqual(u32(14), queue.remove());
expectEqual(u32(15), queue.remove());
expectEqual(u32(15), queue.remove());
expectEqual(u32(16), queue.remove());
expectEqual(u32(21), queue.remove());
expectEqual(u32(22), queue.remove());
expectEqual(u32(24), queue.remove());
expectEqual(u32(24), queue.remove());
expectEqual(u32(25), queue.remove());
const sorted_items = []u32{ 1, 2, 5, 6, 7, 7, 11, 12, 13, 14, 15, 15, 16, 21, 22, 24, 24, 25 };
for (sorted_items) |e| {
expectEqual(e, queue.remove());
}
}
test "std.PriorityQueue: addSlice" {
var queue = PQ.init(debug.global_allocator, lessThan);
defer queue.deinit();
const items = []u32{ 15, 7, 21, 14, 13, 22, 12, 6, 7, 25, 5, 24, 11, 16, 15, 24, 2, 1 };
try queue.addSlice(items[0..]);
const sorted_items = []u32{ 1, 2, 5, 6, 7, 7, 11, 12, 13, 14, 15, 15, 16, 21, 22, 24, 24, 25 };
for (sorted_items) |e| {
expectEqual(e, queue.remove());
}
}
test "std.PriorityQueue: fromOwnedSlice" {
const items = []u32{ 15, 7, 21, 14, 13, 22, 12, 6, 7, 25, 5, 24, 11, 16, 15, 24, 2, 1 };
const heap_items = try std.mem.dupe(debug.global_allocator, u32, items[0..]);
var queue = PQ.fromOwnedSlice(debug.global_allocator, lessThan, heap_items[0..]);
defer queue.deinit();
const sorted_items = []u32{ 1, 2, 5, 6, 7, 7, 11, 12, 13, 14, 15, 15, 16, 21, 22, 24, 24, 25 };
for (sorted_items) |e| {
expectEqual(e, queue.remove());
}
}
test "std.PriorityQueue: add and remove max heap" {