HDU 1301

题意

给出n个编号为A~A+n的节点，和某些节点之间的距离，求最小生成树的总权值

思路

裸的Prim算法求最小生成树
算法细节：
最小生成树-Prim算法和Kruskal算法

AC代码

#include <iostream>
#include <algorithm>
#include <cstdio>
#include <cstring>
#define mst(a) memset(a, 0, sizeof(a))
using namespace std;
typedef long long ll;
const int INF = 0x3f3f3f3f;
const int maxn = 30;
ll all;
int n;
int mc[maxn], d[maxn][maxn], vis[maxn];

void init(){
    all = 0;
    mst(mc);
    mst(d);
    mst(vis);
    for( int i = 1; i <= maxn; i++ ){
        for( int j = 1; j <= maxn; j++ ){
            d[i][j] = i == j ? 0 : INF;
        }
    }
}

ll prim(){
    for( int i = 1; i <= n; i++ ){
        mc[i] = INF;
        vis[i] = 0;
    }
    mc[1] = 0;
    int all = 0;
    for(;;){
        int v = -1;
        for( int i = 1; i <= n; i++ ){
            if(!vis[i] && (v == -1 || mc[i] < mc[v] ) )
                v = i;
        }
        if( v == -1 ) break;
        vis[v] = 1;
        all += mc[v];
        for( int i = 1; i <= n; i++ )
            mc[i] = min(mc[i], d[v][i]);
    }
    return all;
}

int main()
{
    int T, nn, cost;
    char f, t;
    while( scanf("%d",&T) == 1 && T ){
        n = T;
        init();
        getchar();
        for( int i = 1; i < T; i++ ){
            scanf("%c",&f);getchar();
            scanf("%d",&nn);getchar();
            //printf("%c %d
", f, n);
            while(nn--){
                scanf("%c",&t);getchar();
                scanf("%d",&cost);getchar();
                //printf("%c %d
", t, cost);
                int xx = f-'A'+1, yy = t-'A'+1;
                if( cost < d[xx][yy] ){
                    d[xx][yy] = cost;
                    d[yy][xx] = cost;
                }
            }
        }
        printf("%lld
",prim());
    }
    return 0;
}