hdu1874畅通工程续

http://acm.hdu.edu.cn/showproblem.php?pid=1874

floyd: 62MS

#include<iostream>
using namespace std ;
#define maxn 210
const int oo = 1<<28 ;
int map[maxn][maxn] ;
int n ;
void init()
{
    for(int i=0; i<n; i++)
    for(int j=0; j<n; j++)
    {
        map[i][j] = oo ;
        if(i==j)
        map[i][j] = 0 ;
    }
}
void floyd()
{
    for(int k=0; k<n; k++)
    for(int i=0; i<n; i++)
    for(int j=0; j<n; j++)
    if(map[i][j]>map[i][k]+ map[k][j])
    map[i][j] = map[i][k] + map[k][j] ;
}
int main()
{
    int m, a, b, c, s, t ;
    while(cin>>n>>m)
    {
        init() ;
        while(m--)
        {
            cin>>a>>b>>c ;
            if(map[a][b]>c)
            map[a][b] = map[b][a] = c ;
        }
        cin>>s>>t ;
        floyd() ;
        if(map[s][t]<oo)
        cout<<map[s][t]<<endl ;
        else
        cout<<"-1"<<endl ;
    }
    return 0 ;
}

dijkstra: 15MS

#include<iostream>
#include<map>
#include<cstdio>
#include<cstring>
#include<string>
#include<algorithm>
using namespace std;

#define MAX 0x3f3f3f3f
#define N 210
int num, road, dis[N], len[N][N];
bool visit[N];


void Dijkstra(int start)
{
    int k, temp;
    memset(visit, 0, sizeof(visit));
    for(int i = 0; i < num; ++i) //初始化
        dis[i] = (i==start ? 0 : MAX);
    for(int i = 0; i < num; ++i)
    {
        temp = MAX;
        for(int j = 0; j < num; ++j) //查找最短路
            if(!visit[j] && dis[j] < temp)
                temp = dis[k = j];
        visit[k] = 1;
        for(int j = 0; j < num; ++j) //更新源点到其他点的最短路
            if(!visit[j] && dis[j] > dis[k] + len[k][j])
                dis[j] = dis[k] + len[k][j];
    }
}

int main()
{
    int a, b, cost, start, end;
    while(scanf("%d%d", &num, &road) != EOF)
    {
        memset(len, MAX, sizeof(len));
        for(int i = 0; i < road; ++i)
        {
            scanf("%d%d%d", &a, &b, &cost);
            if(cost < len[a][b]) //一条路可以有多个cost，记录最小的。注意~~~
            len[a][b] = len[b][a] = cost;
        }
        scanf("%d%d", &start, &end);
        Dijkstra(start);
        if(dis[end] == MAX) printf("-1\n");
        else printf("%d\n", dis[end]);
    }
    return 0;
}