题解 | 【模板】堆

package main

import (
    "strconv"
	"bufio"
	"container/heap"
    "os"
	"fmt"
)

type MaxHeap []int

func (h MaxHeap) Len() int {
    return len(h)
}

func (h MaxHeap) Less(i,j int) bool {
    return h[i] > h[j]
}

func (h MaxHeap) Swap(i,j int) {
    h[i],h[j] = h[j],h[i]
}

func (h *MaxHeap) Push(x interface{}) {
    *h = append(*h, x.(int))
}

func (h *MaxHeap) Pop() interface{} {
    old := *h
    n := len(old)
    x := old[n-1]
    (*h) = old[:n-1]
    return x
}

func (h *MaxHeap) Top() interface{} {
    return (*h)[0]
}

func main() {
    h := &MaxHeap{}
    heap.Init(h)


    in := bufio.NewReader(os.Stdin)
    out := bufio.NewWriter(os.Stdout)
    var n int
    fmt.Fscan(in, &n)
    for i := 1;i<=n;i++{
        var op string
        var val int

        fmt.Fscan(in, &op)

        switch op {
            case "push":
            fmt.Fscan(in, &val)
            heap.Push(h, val)
            case "pop":
            if len(*h) == 0 {
                out.WriteString("empty")
            } else {
                str := strconv.Itoa(heap.Pop(h).(int))
                out.WriteString(str)
            }
            out.WriteRune('\n')

            case "top":
            if len(*h) == 0 {
                out.WriteString("empty")
            } else {
                str := strconv.Itoa(h.Top().(int))
                out.WriteString(str)
            }
            out.WriteRune('\n')
        }
    }
    out.Flush()


}