XDOJ_1078_分层图最短路

#include<iostream>
#include<cstring>
#include<cstdio>
#include<algorithm>
#include<vector>
#include<queue>
#define INF 0x3f3f3f3f
using namespace std;

struct edge
{
    int to,cost;
    friend bool operator>(edge x,edge y)
    {
        return x.cost > y.cost;
    }
}e;
vector<edge> v[11005];
int n,m,k,a[1005][1005],dis[11005],vis[11005];
priority_queue< edge,vector<edge>,greater<edge> > q;

int dij()
{
    while(!q.empty())    q.pop();
    memset(dis,0x3f,sizeof(dis));
    memset(vis,0,sizeof(vis));
    dis[1] = 0;
    e.to = 1;
    e.cost = 0;
    q.push(e);
    while(!q.empty())
    {
        int now = q.top().to,cost = q.top().cost;
        if(now == (k+1)*n)    return dis[(k+1)*n];
        q.pop();
        if(vis[now])    continue;
        vis[now] = 1;
        for(int i = 0;i < v[now].size();i++)
        {
            e = v[now][i];
            if(e.cost+dis[now] < dis[e.to])
            {
                dis[e.to] = e.cost+dis[now];
                e.cost = dis[e.to];
                q.push(e);
            }
        }

    }
}

int main()
{
    while(~scanf("%d%d%d",&n,&m,&k))
    {
        for(int i = 1;i <= 11000;i++)    v[i].clear();
        memset(a,0x3f,sizeof(a));
        for(int i = 1;i <= m;i++)
        {
            int u,v,w;
            scanf("%d%d%d",&u,&v,&w);
            a[u][v] = min(a[u][v],w);
            a[v][u] = min(a[v][u],w);
        }
        for(int i = 1;i <= n;i++)
        {
            for(int j = 1;j <= n;j++)
            {
                if(i == j || a[i][j] == INF)    continue;
                for(int l = 0;l <= k;l++)
                {
                    e.to = l*n+j;
                    e.cost = a[i][j];
                    v[l*n+i].push_back(e);
                    if(l != k)
                    {
                        e.to = (l+1)*n+j;
                        e.cost = 0;
                        v[l*n+i].push_back(e);
                    }
                }
            }
        }
        printf("%d\n",dij());
    }
    return 0;
}