c/c++语言开发共享加边的无向图–并查集

#include<iostream> #include<cstring> #include<algorithm> #define ll long long using namespace std; ll father[1000010]; void init(){//初始化     for(ll i=1;i<=1000010;i++){         father[i]=i;     } } ll find (int x){//寻找父节点     if(x==father[x]){         return x;     }else{         return father[x]=find(father[x]);     } } void merge(int x,int y){     ll p=find(x);     ll q=find(y);     if(p!=q){/*两个不是一个父节点*/         father[p]=q;     } } int main(){     ll n,m;     cin>>n/*点*/>>m/*边*/;     ll ri,rj;     init();     for(ll i=0;i<m;i++){         cin>>ri>>rj;         merge(ri,rj);     }     ll cnt=-1;     for(ll i=1;i<=n;i++){         if(i==father[i]){             cnt++;         }     }     printf("%lld",cnt);     return 0; }