POJ 3635 Full Tank?

看了别人的结题报告才过的，可以把没增加一滴油当成一个节点，找最短路就行了。。

#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <cmath>
#include <queue>

using namespace std;
const int N = 1009;
const int M = 10009;
const int INF  = 0x3f3f3f3f;
int dp[N][109];
bool visit[N][109];
int val[N],n,m,q,c,st,en;
struct LL{
    int to,dis,nex;
} L[M<<1];
int F[N],cnt;
void add(int f,int t,int d)
{
    L[cnt].dis = d;
    L[cnt].nex = F[f];
    L[cnt].to = t;
    F[f] = cnt++;
}
struct node{
    int i,h,cost;
    bool operator <(const node t) const
    {
        return cost>t.cost;
    }
};
void init()
{
    scanf("%d%d",&n,&m);
    memset(F,0,sizeof(F));
    cnt = 1;
    for(int i=0;i<n;i++) scanf("%d",&val[i]);
    int f,t,d;
    for(int i=0;i<m;i++)
    {
        scanf("%d%d%d",&f,&t,&d);
        add(f,t,d);
        add(t,f,d);
    }
}
void solve()
{
    scanf("%d%d%d",&c,&st,&en);
    memset(dp,INF,sizeof(dp));
    memset(visit,false,sizeof(visit));
    for(int i=0;i<=c;i++)
    dp[st][i] = val[st]*i;
    priority_queue<node> que;
    //visit[st][0] = true;
    while(!que.empty()) que.pop();
    node e,t;
    e.i = st;e.h = 0;e.cost =0;
    que.push(e);
    while(!que.empty())
    {
        e = que.top(); que.pop();
        //cout<<e.i<<" "<<e.h<<" "<<e.cost<<endl;
        if(visit[e.i][e.h]) continue;
        visit[e.i][e.h] = true;
        if(e.i==en)
        {
            dp[e.i][0] = e.cost;
            break;
        }
        if(e.h<c)
        {
            t.i = e.i;
            t.h = e.h+1;
            t.cost =e.cost + val[e.i];
            que.push(t);
        }
        for(int i=F[e.i];i;i=L[i].nex)
        {
            int to = L[i].to;
            if(e.h>=L[i].dis&&!visit[to][e.h-L[i].dis])
            {
                t.i = to;
                t.h = e.h - L[i].dis;
                t.cost =e.cost;
                que.push(t);
            }
        }
    }
    if(dp[en][0]==INF) printf("impossible\n");
    else printf("%d\n",dp[en][0]);
}
int main()
{
    freopen("in.txt","r",stdin);
    init();
    scanf("%d",&q);
    while(q--)
        solve();
    return 0;
}