Roads and Libraries

Roads and Libraries

#include <cstdio>#include <cstring>#include <algorithm>#include <iostream>using namespace std;int a[1000010];int vis[1000010];int f(int x){    if (a[x]==x){        return x;    }    else{        a[x]=f(a[x]);        return a[x];    }}int main(){    int t;    scanf("%d",&t);    while(t--){        long long n,m,x1,x2;        scanf("%lld%lld%lld%lld",&n,&m,&x1,&x2);        for (int i=0;i<=n;i++){            a[i]=i;        }        long long x,y,xx=0;        for (int i=1;i<=m;i++){            scanf("%lld%lld",&x,&y);            a[f(y)]=f(x);        }        if (x1<=x2){            xx=x1*n;            printf("%lld\n",xx);        }        else{            for (int i=1;i<=n;i++)                a[i]=f(a[i]);                memset(vis,0,sizeof(vis));                for (int i=1;i<=n;i++){                    vis[a[i]]++;                }                for (int i=1;i<=n;i++){                    if (vis[i]!=0){                        xx=xx+(vis[i]-1)*x2+x1;                    }                }            printf("%lld\n",xx);        }    }    return 0;}