Created
June 16, 2022 16:07
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generic heap
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package main | |
type Heap[T any] struct { | |
data []T | |
compare func(a, b T) bool | |
} | |
func CreateHeap[T any](compare func(a, b T) bool) *Heap[T] { | |
return &Heap[T]{compare: compare} | |
} | |
func parent(i int) int { | |
return (i - 1) / 2 | |
} | |
func left(i int) int { | |
return (i * 2) + 1 | |
} | |
func right(i int) int { | |
return left(i) + 1 | |
} | |
func (h *Heap[T]) Length() int { | |
return len(h.data) | |
} | |
func (h *Heap[T]) Push(value T) { | |
h.data = append(h.data, value) | |
h.up(h.Length() - 1) | |
} | |
func (h *Heap[T]) Pop() T { | |
n := h.Length() - 1 | |
if n > 0 { | |
h.swap(0, n) | |
h.down() | |
} | |
v := h.data[n] | |
h.data = h.data[0:n] | |
return v | |
} | |
func (h *Heap[T]) swap(i, j int) { | |
h.data[i], h.data[j] = h.data[j], h.data[i] | |
} | |
func (h *Heap[T]) up(j int) { | |
for { | |
i := parent(j) | |
if i == j || !h.compare(h.data[j], h.data[i]) { | |
break | |
} | |
h.swap(i, j) | |
j = i | |
} | |
} | |
func (h *Heap[T]) down() { | |
n := h.Length() - 1 | |
i1 := 0 | |
for { | |
j1 := left(i1) | |
if j1 >= n || j1 < 0 { | |
break | |
} | |
j := j1 | |
j2 := right(i1) | |
if j2 < n && h.compare(h.data[j2], h.data[j1]) { | |
j = j2 | |
} | |
if !h.compare(h.data[j], h.data[i1]) { | |
break | |
} | |
h.swap(i1, j) | |
i1 = j | |
} | |
} |
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