poj2421

这题是prim稍微变形了一下。只要把建好路的两点map[i][j]置为0，就ok了。搜easy

#include<cstdio>
#include<cstring>

const int INF=1e9;
int map[105][105];
int low[105],vis[105];

void prim(int from,int m)
{
    memset(vis,0,sizeof(vis));
    for(int i=1;i<=m;i++)low[i]=map[from][i];
    low[from]=0;
    vis[from]=1;
    for(int i=1;i<=m;i++){
        int x,MIN=INF;
        for(int y=1;y<=m;y++){
            if(!vis[y]&&low[y]<MIN)
                MIN=low[x=y];
        }
        vis[x]=1;
        for(int y=1;y<=m;y++){
            if(!vis[y]&&low[y]>map[x][y])
                low[y]=map[x][y];
        }
    }
}

int main()
{
    //freopen("in.txt","r",stdin);
    int n;
    scanf("%d",&n);
    int cas=n;
    for(int i=1;i<=n;i++){
        for(int j=1;j<=n;j++)
            scanf("%d",&map[i][j]);
    }
    int q;
    scanf("%d",&q);
    int from,to;
    while(q--){
        scanf("%d%d",&from,&to);
        map[from][to]=map[to][from]=0;
    }
    prim(1,n);
    int sum=0;
    for(int i=1;i<=n;i++)sum+=low[i];
    printf("%d\n",sum);
    return 0;
}