模板 - 左偏树

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;

int n, m;
const int MAXN = 1000005;
int tot, v[MAXN], l[MAXN], r[MAXN], d[MAXN];
int gc[MAXN];   //gc[i]表示编号为i的工厂所在的左偏树是哪个x

class Leftist_Tree {
    int _Merge(int x, int y) {
        if(!x || !y)
            return x + y;
        if(v[x] < v[y])
            swap(x, y);
        r[x] = _Merge(r[x], y);
        if(d[l[x]] < d[r[x]])
            swap(l[x], r[x]);
        d[x] = d[r[x]] + 1;
        return x;
    }
    int Build(int val = -1) {
        tot++;
        l[tot] = r[tot] = d[tot] = 0;
        v[tot] = val;
        return tot;
    }
  public:
    void Init(int n) {
        tot = n; //当前树的上界到了哪个
        for(int i = 1; i <= n; i++) {
            l[i] = r[i] = d[i] = 0;
            v[i] = -1;
        }
        l[0] = r[0] = -1;
        d[0] = 0;
        v[0] = -1;
    }

    void Push(int x, int val) {
        int gcx = gc[x];
        int rt = Build(val);
        rt = _Merge(rt, gcx);
        gc[x] = rt;
    }
    int Pop(int x) {
        //把x工厂的左偏树的顶端弹出，没有顶端弹出-1
        int gcx = gc[x];
        if(v[gcx] == -1)
            return -1;
        int res = v[gcx];
        gc[x] = _Merge(l[gcx], r[gcx]);
        return res;
    }
    void Merge(int x, int y) {
        //把编号x与编号y的工厂合并到x工厂
        int gcx = gc[x];
        int gcy = gc[y];
        gc[x] = _Merge(gcx, gcy);
        gc[y] = Build();
    }
} lt;


int main() {
#ifdef Yinku
    freopen("Yinku.in", "r", stdin);
#endif // Yinku
    int n, m;
    scanf("%d%d", &n, &m);
    lt.Init(n);
    for(int i = 1; i <= m; i++) {
        int ins;
        scanf("%d", &ins);
        switch(ins) {
        case 1: {
            int x, v;
            scanf("%d%d", &x, &v);
            lt.Push(x, v);
            break;
        }
        case 2: {
            int x, y;
            scanf("%d%d", &x, &y);
            lt.Merge(x, y);
            break;
        }
        case 3: {
            int x;
            scanf("%d", &x);
            printf("%d\n", lt.Pop(x));
            break;
        }
        }
    }
}