#include <iostream>
using namespace std;
#define INFINE 99999999//假装自己是无穷大
const int N = 1010;
int graph[N][N];
int vertexnum, arcnum;
//lowcost[i]:表示以i为终点的边的最小权值,
//当lowcost[i]=0说明以i为终点的边的最小权值=0,
//也就是表示i点加入了MST//mst[i]:表示对应lowcost[i]的起点，
//即说明边<mst[i],i>是MST的一条边
void Prim(int v, int n) {int sum = 0;int locatest[N];int mst[N];for (int i = 1; i <= n; i++) {locatest[i] = graph[v][i];mst[i] = v;}mst[v] = 0;locatest[v] = 0;for (int i = 2; i <= n; i++) {int minx = INFINE;int minid = 0;for (int k = 1; k <= n; k++) {if (locatest[k] != 0 && locatest[k] < minx) {minx = locatest[k];minid = k;}}cout << "V" << mst[minid] << "-" << "V" << minid << " = " << minx << endl;locatest[minid] = 0;sum += minx;for (int i = 1; i <= n; i++) {if ( graph[minid][i] < locatest[i]) {locatest[i] = graph[minid][i];mst[i] = minid;}}}cout << sum << endl;return;
}void CreateGraph() {cin >> vertexnum >> arcnum;//输入点的个数，边的条数for (int i = 1; i <= vertexnum; i++)for (int j = 1; j <= vertexnum; j++)graph[i][j] = INFINE;for (int i = 1; i <= arcnum; i++) {int a, b, w;cin >> a >> b >> w;graph[a][b] = w;//无向图,故两边都要赋值graph[b][a] = w;}
}int main() {CreateGraph();Prim(1, vertexnum);//以点1为最小生成树的起点return 0;
}

最小生成树Prim算法理解地址:
https://blog.csdn.net/yeruby/article/details/38615045