计算最小生成树代价和

题目网址:

http://codeup.cn/problem.php?cid=100000985&pid=0

/**
    普里姆算法构造最小生成树
*/
#include <stdio.h>
#define N 105
#define INF 60000
int G[N][N],n;
typedef struct {
    int dist;
    int data;
}Closedge;
int ans;
void prim(int s){///从s结点查找
    int flag[N];///标记是否被选中
    Closedge closedge[N];
    for(int i = 0; i < N; i++) {
        flag[i] = 0;
        closedge[i].dist = G[s][i];
        closedge[i].data = s;
    }
    int m = 0,min;
    flag[s] = 1;
    while(m < n - 1){///加n-1个点
        min = 0;
        ///选出最小的那个
        for(int i = 0; i < n; i++){
            if(closedge[min].dist > closedge[i].dist)
                min = i;
        }
        ///入选min点
        flag[min] = 1;
        closedge[min].dist = INF;
        ans += G[closedge[min].data][min];
        ///更新closedge数组
        for(int j = 0; j < n; j++)
            ///min与j直接相连
            ///j点是没有入选的点
            ///结点min到结点j < closeage.[data]
            if(G[min][j] < closedge[j].dist && G[min][j]!=0 && !flag[j]){
                closedge[j].dist = G[min][j];
                closedge[j].data = min;
            }
        m++;
    }
}
int main(void){
    while(scanf("%d",&n) != EOF){
        for(int i = 0; i < n; i++)
        for(int j = 0; j < n; j++){
            scanf("%d",&G[i][j]);
            if(G[i][j] == 0)
                G[i][j] = INF;
        }
        ans = 0;
        prim(0);
        printf("%d
",ans);
    }
    return 0;
}