hdoj2680选择最佳路径

#include<iostream>
#include<queue>
#include<cstring>
using namespace std;
const int N = 1010, M = 20010, inf = 0x3f3f3f3f;
int n, m, s, T;
int q[N], dist[N], w[M];
int h[N], e[M], ne[M], idx;
bool st[N];

void add(int a, int b, int c){
    e[idx] = b, ne[idx] = h[a], w[idx] = c, h[a] = idx ++ ;
}

int spfa()
{
    memset(dist, 0x3f, sizeof dist);
    q[0] = 0;
    dist[0] = 0;
    int hh = 0, tt = 1;
    while (hh != tt)
    {
        int t = q[hh ++ ];
        if (hh == N) hh = 0;

        st[t] = false;
        for (int i = h[t]; ~i; i = ne[i])
        {
            int j = e[i];
            if (dist[j] > dist[t] + w[i])
            {
                dist[j] = dist[t] + w[i];
                if (!st[j])
                {
                    q[tt ++ ] = j;
                    if (tt == N) tt = 0;
                    st[j] = true;
                }
            }
        }
    }
    if(dist[T] == inf) return -1;
    return dist[T];
}


int main()
{
    while (scanf("%d%d%d", &n, &m, &T) != -1)
    {
        memset(h, -1, sizeof h);
        idx = 0;

        while (m -- )
        {
            int a, b, c;
            scanf("%d%d%d", &a, &b, &c);
            add(a, b, c);
        }
        scanf("%d", &s);
        while(s -- ){
            int ver;
            scanf("%d", &ver);
            add(0, ver, 0);
        }
        printf("%d\n", spfa());
    }

    return 0;
}

解法:

创建一个虚起点， 建立与实原点建立一条边权为0的边