题目：

提示：

Floyd最短路径算法实现(未测试)：

//
//  main.cpp
//  Alg_Floyd_playgame
//
//  Created by wasdns on 16/11/19.
//  Copyright ? 2016年 wasdns. All rights reserved.
//  #include <iostream>
#include <cstdio>
#include <cstdlib>
#include <string>
#include <string.h>
using namespace std;  #define endless 1000000001;  int Floydgh[5005][5005];  void Inigh(int n)
{  for (int i = 1; i <= n; i++)  {  Floydgh[i][i] = 0;  for (int j = 1; j <= n; j++)  {  if (i != j) {  Floydgh[i][j] = endless;  }  }  }
}  void Creatgh(int n, int m)
{  Inigh(n);  int i, u, v, w;  for (i = 1; i <= m; i++)  {  cin >> u >> v >> w;  Floydgh[u][v] = w;  Floydgh[v][u] = w;  }
}  void Alg_Floyd(int n)
{  int i, j, k;  for (k = 1; k <= n; k++)  {  for (i = 1; i <= n; i++)  {  for (j = 1; j <= n; j++)  {  int t = Floydgh[i][k] + Floydgh[k][j];  if (t < Floydgh[i][j]) {  Floydgh[i][j] = t;  Floydgh[j][i] = t;  }  }  }  }
}  int minjudge(int n)
{  int i, j;  int minlen = endless;  for (i = 1; i <= n; i++)  {  int cnt = 0;  for (j = 1; j <= n; j++)  {  cnt += Floydgh[i][j];  }  if (cnt < minlen) {  minlen = cnt;  }  }  return minlen;
}  int main()
{  int n, m;  cin >> n >> m;  Creatgh(n, m);  Alg_Floyd(n);  cout << minjudge(n) << endl;  return 0;
}

Prim生成树算法实现：

关于Prim算法，请参考我的另外一篇博客：hdoj-1233-还是畅通工程

//
//  main.cpp
//  Prim
//
//  Created by wasdns on 16/11/24.
//  Copyright © 2016年 wasdns. All rights reserved.
//#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <algorithm>
#include <string>
#include <string.h>
#define maxn 10000005;
using namespace std;int Primgh[10000][10000];bool refer[10005];void Initial(int n, int m)
{int i, j;for (i = 1; i <= n; i++){refer[i] = false;for (j = 1; j <= n; j++){if (i == j) {Primgh[i][j] = 0;}else Primgh[i][j] = maxn;}}int u, v, w;for (i = 1; i <= m; i++){cin >> u >> v >> w;Primgh[u][v] = w;Primgh[v][u] = w;}
}int Prim_Alg(int n, int m)
{Initial(n, m);int i, j, k;int ans = 0;refer[1] = true;                    //起点为1for (i = 1; i <= n-1; i++){int minlen = maxn;int rcd = 1;for (j = 1; j <= n; j++){if (!refer[j]) continue;int len1 = maxn;int rcd1 = 1;for (k = 1; k <= n; k++){if (!refer[k]){if (Primgh[j][k] < len1) {len1 = Primgh[j][k];rcd1 = k;}}}if (len1 < minlen) {minlen = len1;rcd = rcd1;}}//char check = 'A'+rcd-1;//cout << "rcd: " << check << endl;//cout << "minlen: " << minlen << endl;refer[rcd] = true;rcd = 1;ans += minlen;}return ans;
}int main()
{int n, m;cin >> n >> m;cout << Prim_Alg(n, m) << endl;return 0;
}

测试样例：

/*eg1. Input:4 61 2 12 3 21 3 32 4 33 4 51 4 4Output:6eg2.Input:7 111 2 71 4 52 4 92 3 82 5 73 5 54 5 154 6 65 6 85 7 96 7 11Output:39*/

2016/11/24