nyoj 115 城市平乱 dijkstra最短路

题目链接： http://acm.nyist.net/JudgeOnline/problem.php?pid=115

dijkstra算法。

#include "stdio.h"
#include "string.h"

#define N 1005
#define INF 0x3fffffff
bool vis[N];
int map[N][N];

bool mark[N];
int dist[N];

int dij(int start,int n)
{
    int mint;
    int i,j,k;
    memset(mark,false,sizeof(mark));
    mark[start] = true;
    for(i=1;i<=n; ++i)
        dist[i] = map[start][i];
    for(i=2; i<=n; ++i)
    {
        k = -1;
        mint = INF;
        for(j=1; j<=n; ++j)
        {
             if(!mark[j] && mint>dist[j])
             {
                 mint = dist[j];
                 k = j;
             }
        }
        mark[k] = true;
        if(vis[k]) return dist[k];
        for(j=1; j<=n; ++j)
        {
            if(!mark[j] && dist[j] > dist[k]+map[k][j])
                dist[j] = dist[k]+map[k][j];
        }
    }
}

int main()
{
    int T;
    int i,j;
    int x,y,k;
    int n,m,p,start;
    scanf("%d",&T);
    while(T--)
    {
        memset(vis,false,sizeof(vis));
        scanf("%d %d %d %d",&n,&m,&p,&start);
        for(i=0; i<n; ++i)
        {
            scanf("%d",&k);
            vis[k] = true;
        }
        for(i=1; i<=m; ++i)
        {
            for(j=1; j<=m; ++j)
                map[i][j]=INF;
        }
        while(p--)
        {
            scanf("%d %d %d",&x,&y,&k);
            if(k<map[x][y])
                map[x][y]=map[y][x]=k;
        }
        printf("%d\n",dij(start,m));
    }
    return 0;
}
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