08. heap

package main

import "container/heap"

type IntHeap []int

func (h IntHeap) Len() int           { return len(h) }
// func (h IntHeap) Less(i, j int) bool { return h[i] < h[j] } // 小顶堆
func (h IntHeap) Less(i, j int) bool { return h[i] > h[j] }    // 大顶堆
func (h IntHeap) Swap(i, j int)      { h[i], h[j] = h[j], h[i] }
func (h *IntHeap) Push(x any)        { *h = append(*h, x.(int)) }
func (h *IntHeap) Pop() any {
    old := *h
    n := len(old)
    x := old[n - 1]
    *h = old[0:n - 1]
    return x
}

func main() {
    h := &IntHeap{2, 1, 5}
    heap.Init(h)
    heap.Push(h, 3)
    minv := heap.Pop(h)
    fmt.Println(minv) // 5
}