dp uva1025

题目链接

#include <bits/stdc++.h>
using namespace std;

const int INF = 1<<30;
const int maxn = 50+5;
const int maxt = 200+5;
int N,T,a[maxn],t[maxn],M1,d,M2,e,dp[maxt][maxn],kase;
bool has_train[maxt][maxn][2];


void solve(){
    for(int i=1; i<=N-1; i++) dp[T][i] = INF;
    dp[T][N] = 0;

    for(int i=T-1; i>=0; i--){
        for(int j=1; j<=N; j++){
            dp[i][j] = dp[i+1][j]+1;
            if(j<N && has_train[i][j][0] && i+t[j]<=T)
                dp[i][j] = min(dp[i][j],dp[i+t[j]][j+1]);
            if(j>1 && has_train[i][j][1] && i+t[j-1]<=T)
                dp[i][j] = min(dp[i][j],dp[i+t[j-1]][j-1]);
        }
    }


    cout << "Case Number " << ++kase << ": ";
    if(dp[0][1] >= INF) cout << "impossible
";
    else cout << dp[0][1] << endl;
}

int main(){

    while(cin>>N && N){
        memset(has_train,0,sizeof(has_train));
        cin >> T;
        for(int i=1; i<=N-1; i++)
            cin >> t[i];
        cin >> M1;
        for(int i=0; i<M1; i++){
            cin >> d;
            for(int j=1; j<=N-1; j++){
                if(d <= T)
                    has_train[d][j][0] = 1;
                d += t[j];

            }
        }

        cin >> M2;
        for(int i=0; i<M2; i++){
            cin >> e;
            for(int j=N-1; j>=1; j--){
                if(e <= T)
                    has_train[e][j+1][1] = 1;
                e += t[j];
            }
        }


        solve();
    }

}