HDU 1102 Constructing Roads

很好的最小生成树的模板题，由于用邻接矩阵存储的，故用prim算法比较方便。

AC code：

#include <iostream>
using namespace std;
int n, q, sum;
const int MAX = 101;
const int INF = 100000;
int map[MAX][MAX], vis[MAX], dis[MAX];

void init()
{
    int i, j, tx, ty;
    for(i = 1; i <= n; i++){
        for(j = 1; j <= n; j++)
        scanf("%d", &map[i][j]);
    }
    scanf("%d", &q);
    for(i = 1; i <= q; i++){
        scanf("%d%d", &tx, &ty);
        map[tx][ty] = 0;
        map[ty][tx] = 0;
    }
}
void prim()
{
    int i, j;
    sum = 0;
    memset(vis, 0, sizeof(vis));
    for(i = 1; i <= n; i++)
        dis[i] = INF;
    dis[1] = 0;
    for(i = 1; i <= n; i++){
        int min = INF, pos = -1;
        for(j = 1; j <= n; j++){
            if(dis[j] < min && !vis[j]){
                min = dis[j];
                pos = j;
            }
        }
        vis[pos] = 1;
        sum += min;
        for(j = 1; j <= n; j++){
            if(map[pos][j] < dis[j])
                dis[j] = map[pos][j];
        }
    }
}
int main()
{
    while(scanf("%d", &n) != EOF)
    {
         init();
         prim();
         printf("%d\n", sum);
    }
    return 0;
}