POJ1258《Agri-Net》方法：Prim

非常典型的找最小生成树。

#include <iostream>#include <cstdio>#include <cstring>using namespace std;const int inf = 0x7fffffff;int n; //节点数int w[101][101]; //边权int dis[101];bool v[101];void prim(){int s = 1, sum = 0, min;dis[s] = 0;v[s] = true;for (int i = 2; i <= n; ++i) {dis[i] = w[i][1];v[i] = false;}for (int i = 1; i <= n-1; ++i) {min = inf;for (int j = 1; j <= n; ++j) {if (!v[j] && dis[j] < min) {min = dis[j];s = j;}}v[s] = true;sum += min;for (int j = 1; j <= n; ++j) {if (!v[j] && dis[j] > w[s][j]) {dis[j] = w[s][j];}}}cout << sum << endl;}int main(){//freopen("temp.txt", "r", stdin);while (cin >> n) {for (int i = 1; i <= n; ++i) for (int j = 1; j <= n; ++j)cin >> w[i][j];prim();}return 0;}