//kruskal算法
#include<iostream>
#include<cstring>
#include<queue>
using namespace std;
const int maxn=120;
struct Edge
{int v,u,weight;bool friend operator < (Edge a,Edge b){return a.weight>b.weight;}
};
//并查集模板
int pre[maxn];
int get_parent(int x)
{if(-1==pre[x])   return x;return pre[x]=get_parent(pre[x]);
}
bool mix (int x,int y)
{int fx=get_parent(x),fy=get_parent(y);if(fx==fy)return 1;pre[fx]=fy;return 0;
}priority_queue<Edge> E;
int kruskal()
{int cost=0;while(!E.empty()){Edge now=E.top();E.pop();if(!mix(now.v,now.u)){//不在同一个集合中cost+=now.weight;}}return cost;
}
int main()
{int n;while(cin>>n){while(!E.empty())   E.pop();memset(pre,-1,sizeof(pre));Edge e;for(int i=1;i<=n;i++){e.v=i;for(int j=1;j<=n;j++){e.u=j;cin>>e.weight;if(i<j) E.push(e);}}int q,a,b;cin>>q;while(q--){cin>>a>>b;mix(a,b);}int ans=kruskal();cout<<ans<<endl;}return 0;
}

2.Prime算法

#include<iostream>
#include<cstdio>
#include<cstring>
using namespace std;
#define MAX_SIZE 105
int parent[MAX_SIZE];            //记录父节点
int E[MAX_SIZE][MAX_SIZE];       //边集合
int Prim(int N);
bool visit[MAX_SIZE];            //判断该顶点是否在集合里面
int main(){int Q, N, i, j, v, w, ans;while (scanf("%d",&N)!=EOF){memset(visit, 0, sizeof(visit));    //初始化for (i = 1; i <= N; i++)for (j = 1; j <= N; j++)scanf("%d",&E[i][j]);            //输入边scanf("%d", &Q);for (i = 0; i < Q; i++){scanf("%d%d",&v,&w);E[v][w] = E[w][v] = 0;     //已建好将权值设为0}//-----------------------ans = Prim(N);printf("%d\n",ans);}return 0;
}
int Prim(int N){int i, j, k,pos,lmin,ans;parent[1] =-1;         //设置根节点visit[1] = 1;          //表示顶点 1已加入树中int LowCost[MAX_SIZE];for (i = 1; i <= N; i++)LowCost[i] = INT_MAX;      //初始化ans = 0;j = 1;for (i = 2; i <= N; i++){/*j表示上一次加入集合的顶点*/for (k = 1; k <= N; k++){if (!visit[k] && LowCost[k] > E[k][j]){   //更新j的邻接点parent[k] = j;           //将k父节点暂定为 jLowCost[k] = E[k][j];}}lmin = INT_MAX, pos = 0;for (k = 1; k <= N; k++){       //找出不在树中且离树距离最小的点if (!visit[k]&&lmin > LowCost[k]){pos = k;lmin = LowCost[k];}}visit[pos] = 1;      //加入树中ans += E[pos][parent[pos]];  //加入边j = pos;       //更新j}return ans;
}