冬季练习

来源：互联网发布：centos 集成环境编辑：程序博客网时间：2024/06/02 23:21

lightOJ 1040

一个简单的最小生成树的问题，只要注意取一个最小值就可以了。还是比较轻松的。

#include <iostream>#include <cstdio>#include <cstring>#include <algorithm>using namespace std;const int MAXN = 55;const int INF = 0x3f3f3f3f;int mat[MAXN][MAXN];int n;int dist[MAXN];bool vis[MAXN];int solve(int sum){    int begin = 1;    for(int i = 1;i <= n;i++){        if(i == begin) dist[i] = 0;        else dist[i] = min(mat[begin][i],mat[i][begin]);    }    int dv,ds;    memset(vis,false,sizeof vis);    vis[begin] = true;    int res = 0;    for(int cas = 1;cas < n;cas ++){        dv = -1;        ds = INF;        for(int i=1;i<=n;i++){            if(!vis[i] && dist[i] < ds){                dv = i;                ds = dist[i];            }        }        if(dv == -1) return -1;        vis[dv] = true;        res += ds;        for(int i=1;i<=n;i++){            if(!vis[i] && dist[i] > min(mat[dv][i],mat[i][dv])){                dist[i] = min(mat[dv][i],mat[i][dv]);            }        }    }    return sum - res;}int main(){    int T,nc = 1;    scanf("%d",&T);    while(T--){        scanf("%d",&n);        int sum = 0;        for(int i = 1;i<=n;i++) {            for(int j = 1;j<=n;j++) {                scanf("%d",&mat[i][j]);                sum += mat[i][j];                if(mat[i][j] == 0) mat[i][j] = INF;            }        }        // prim();        printf("Case %d: %d\n",nc++,solve(sum));    }    return 0;}

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