数据结构————手写堆

之前堆都是直接用stl中的priority_queue,一直不会手写堆，所以今天搞一下这个手写堆。

洛谷P3378堆的板子

#include<cstdio>
#include<iostream>
using namespace std;
int tree[2000003],t,n;
void change(int a,int b)
{
    int temp = tree[a];
    tree[a] = tree[b];
    tree[b] = temp;
}
void del(int x)
{
    int d = x,f = 0;
    while(x * 2 <= t && f == 0)
    {
        if(tree[x] > tree[x * 2] && x * 2 <= t)
        {
            d = x * 2;
        }
        if(tree[x] > tree[x * 2 + 1] && tree[x * 2 + 1] < tree[x * 2] && x * 2 + 1 <= t)
        {
            d = x * 2 + 1;
        }
        if(x != d)
        {
            change(x,d);
            x = d;
        }
        else
        f = 1;
    }
}
void insert(int x)
{
    int d,f = 0;
    while(x != 1 && f == 0)
    {
        if(tree[x / 2] > tree[x])
        {
            d = x / 2;
            change(x,d);
        }
        else
        f = 1;
        x = x / 2;
    }
}
int main()
{
    scanf("%d",&n);
    int m,k;
    for(int i = 1;i <= n;i++)
    {
        scanf("%d",&m);
        if(m == 1)
        {
            scanf("%d",&k);
            t++;
            tree[t] = k;
            insert(t);
        }
        if(m == 2)
        {
            printf("%d\n",tree[1]);
        }
        if(m == 3)
        {
            tree[1] = tree[t];
            t--;
            del(1);
        }
    }
    return 0;
}

挺好理解的。