[2016-04-14][POJ][1258][Agri-Net]

• 时间:2016-04-14 20:36:55 星期四

• 题目编号:[2016-04-14][POJ][1258][Agri-Net]

• 题目大意:求最小生成树

• 分析:直接prim算法

#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
const int maxn = 100 + 10 ;
int g[maxn][maxn],vis[maxn],lowc[maxn];
int prim(int n){
        int ans = 0;
        memset(vis,0,sizeof(vis));
        vis[0] = 1;
        for(int i = 1 ; i < n ; ++i)        lowc[i] = g[0][i];
        for(int i = 1 ; i < n ;++i){
                int minc = 0x3f3f3f3f;
                int p = -1;
                for(int j = 0 ; j < n ; ++j){
                        if(!vis[j] && minc > lowc[j]){
                                minc = lowc[j];
                                p = j;
                        }
                }
                if(minc == 0x3f3f3f3f)        return -1;
                ans += minc;
                vis[p] = 1;
                for(int j = 0 ; j < n ; ++j){
                        if(!vis[j] && lowc[j] > g[p][j]){
                                lowc[j] = g[p][j];
                        }
                }
        }
        return ans;
}
int main(){
        int n,a;
        while(~scanf("%d",&n)){
                memset(g,0x3f,sizeof(g));
                for(int i = 0 ; i < n ; ++i){
                        for(int j = 0 ; j < n ; ++j){
                                scanf("%d",&a);
                                g[i][j] = min(g[i][j],a);
                        }                       
                }
                printf("%d\n",prim(n));
        }
        return 0;
}

来自为知笔记(Wiz)