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authorRose Hogenson <rosehogenson@posteo.net>2025-04-15 17:24:29 -0700
committerRose Hogenson <rosehogenson@posteo.net>2025-04-15 17:24:29 -0700
commit9c9dc6b65c4b2775e0ba5686d43b0c224fd02836 (patch)
treece93473e6da18bcd4a289ebf3d630888892a849c /heap/heap.go
parentRemove some functions that weren't supposed to be there. (diff)
downloaddeque-9c9dc6b65c4b2775e0ba5686d43b0c224fd02836.tar.zst
Just deque
Diffstat (limited to 'heap/heap.go')
-rw-r--r--heap/heap.go87
1 files changed, 0 insertions, 87 deletions
diff --git a/heap/heap.go b/heap/heap.go
deleted file mode 100644
index 612d5a8..0000000
--- a/heap/heap.go
+++ /dev/null
@@ -1,87 +0,0 @@
-// Package heap implements a priority queue as a min heap backed by a slice.
-//
-// This can be seen as a replacement for the standard library [container/heap]
-// package which was created before generics were a thing.
-package heap
-
-import (
- "slices"
-)
-
-// Heap is a binary heap backed by a slice.
-type Heap[T any] struct {
- buf []T
- compare func(T, T) int
-}
-
-// New creates a new heap with the given comparison function.
-func New[T any](compare func(T, T) int) *Heap[T] {
- return &Heap[T]{compare: compare}
-}
-
-// Len returns the number of elements in the Heap.
-func (h *Heap[T]) Len() int {
- return len(h.buf)
-}
-
-// Grow makes space for at least n more elements to be pushed onto the heap
-// without reallocating.
-func (h *Heap[T]) Grow(n int) {
- h.buf = slices.Grow(h.buf, n)
-}
-
-// Push pushes the element x onto the heap.
-// The complexity is O(log n) where n = h.Len().
-func (h *Heap[T]) Push(x T) {
- n := len(h.buf)
- h.buf = append(h.buf, x)
- h.up(n)
-}
-
-// Pop removes and returns the minimum element (according to Less) from
-// the heap. The complexity is O(log n) where n = h.Len().
-func (h *Heap[T]) Pop() (T, bool) {
- if len(h.buf) == 0 {
- var zero T
- return zero, false
- }
- x := h.buf[0]
- last := h.buf[len(h.buf)-1]
- h.buf = h.buf[:len(h.buf)-1]
- if len(h.buf) > 0 {
- h.down(0, last)
- }
- return x, true
-}
-
-func (h *Heap[T]) up(j int) {
- x := h.buf[j]
- for {
- i := (j - 1) / 2 // parent
- if i == j || h.compare(x, h.buf[i]) >= 0 {
- break
- }
- h.buf[j] = h.buf[i]
- j = i
- }
- h.buf[j] = x
-}
-
-func (h *Heap[T]) down(i int, x T) {
- for {
- j1 := 2*i + 1
- if j1 >= len(h.buf) || j1 < 0 { // j1 < 0 after int overflow
- break
- }
- j := j1 // left child
- if j2 := j1 + 1; j2 < len(h.buf) && h.compare(h.buf[j2], h.buf[j1]) < 0 {
- j = j2 // = 2*i + 2 // right child
- }
- if h.compare(x, h.buf[j]) <= 0 {
- break
- }
- h.buf[i] = h.buf[j]
- i = j
- }
- h.buf[i] = x
-}