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左偏树

https://www.luogu.org/problem/P3377

知识点:1.并查集路径压缩:注意赋值

    2.顺带讲一下,这题裸的并查集是过不了的,要用路径压缩,但是路径压缩会破坏树的性质,所以在删根节点的时候,记得把根节点的父亲指向新的根节点

  

#include <bits/stdc++.h>
#define N 100010
using namespace std;
int ch[N][2],val[N],dis[N],f[N],n,m;
int merge(int x,int y)
{
    if (x == 0 || y == 0)
        return x + y;
    if (val[x] > val[y] || (val[x] == val[y] && x > y))
        swap(x,y);
    ch[x][1] = merge(ch[x][1],y);
    if (dis[ch[x][0]] < dis[ch[x][1]])
        swap(ch[x][0],ch[x][1]);
    dis[x] = dis[ch[x][1]] + 1;
    f[ch[x][1]] = f[ch[x][0]] = x;
    return x;
}
int getf(int x)
{
    if(f[x] == x)return x;
    else return f[x] = getf(f[x]);
}
void pop(int x)
{
    val[x] = -1;
    f[ch[x][0]] = ch[x][0];
    f[ch[x][1]] = ch[x][1];
    f[x] = merge(ch[x][0],ch[x][1]);
}
int main()
{
    scanf("%d%d",&n,&m);
    dis[0] = -1;
    for(int i = 1;i <= n;i++)
        scanf("%d",&val[i]);
    for(int i = 1;i <= n;i++)
        f[i] = i;
    int opt,x,y;
    while(m--)
    {
        scanf("%d",&opt);
        if (opt == 1)
        {
            scanf("%d%d",&x,&y);
            if (val[x] == -1 || val[y] == -1)
                continue;
            if (x == y)
                continue;
            int fx = getf(x),fy = getf(y);
            merge(fx,fy);
        }
        else
        {
            scanf("%d",&x);
            if (val[x] == -1)
                puts("-1");
            else
            {
                int z = getf(x);
                printf("%d\n",val[z]);
                pop(z);
            }
        }
    }
    return 0;
}

 

转载于:https://www.cnblogs.com/xyj1/p/11376112.html

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