Joyride Gym - 101873C

 https://cn.vjudge.net/problem/Gym-101873C

#include <iostream>
#include <cstring>
#include <queue>
#include <vector>
#include <algorithm>
#include <cstdio>
#include <set>
#include <map>
#include <tr1/unordered_map>
#include <cmath>
//#include<bits/stdc++.h>
using namespace std;

#define sfi(i) scanf("%d",&i)
#define sfl(i) scanf("%I64d",&i)
#define sfs(i) scanf("%s",(i))
#define pri(i) printf("%d\n",i)
#define prl(i) printf("%I64d\n",i)
#define sff(i) scanf("%lf",&i)
#define ll long long
#define ull unsigned long long
#define mem(x,y) memset(x,y,sizeof(x))
#define INF 0x3f3f3f3f
#define inf 1e18
#define eps 1e-10
#define PI acos(-1.0)
#define lowbit(x) ((x)&(-x))
#define fl() printf("flag\n")
#define MOD(x) ((x%mod)+mod)%mod
#define endl '\n'
#define pb push_back
#define lson (rt<<1)
#define rson (rt<<1|1)
#define FAST_IO ios::sync_with_stdio(false);cin.tie(0);cout.tie(0)

template<typename T>inline void read(T &x)
{
    x=0;
    static int p;p=1;
    static char c;c=getchar();
    while(!isdigit(c)){if(c=='-')p=-1;c=getchar();}
    while(isdigit(c)) {x=(x<<1)+(x<<3)+(c-48);c=getchar();}
    x*=p;
}

//-----------------------------------------------

const int maxn=1e3+9;
const int mod=1e9+7;

int x,n,m,tt;
int t[maxn],p[maxn];
ll dp[maxn][maxn];
vector<int>g[maxn];

ll dfs(int u,ll sum)
{
    if(sum>x) return inf;
    if(dp[u][sum]!=-1) return dp[u][sum];
    if(u==1&&sum==x) return p[1];
    dp[u][sum]=inf;
    for(int i=0;i<g[u].size();i++)
    {
        int v=g[u][i];
        dp[u][sum]=min(dp[u][sum],dfs(v,sum+tt+t[v])+p[v]);
    }
    dp[u][sum]=min(dp[u][sum],dfs(u,sum+t[u])+p[u]);
    return dp[u][sum];
}

int main()
{
    //FAST_IO;
    //freopen("input.txt","r",stdin);

    mem(dp,-1);
    cin>>x;
    cin>>n>>m>>tt;

    for(int i=1;i<=m;i++)
    {
        int u,v;
        cin>>u>>v;
        g[u].pb(v);
        g[v].pb(u);

    }
    for(int i=1;i<=n;i++) cin>>t[i]>>p[i];

    ll ans=dfs(1,t[1]);

    if(2*t[1]>x||ans==inf) cout<<"It is a trap."<<endl;
    else cout<<ans<<endl;
    return 0;
}