递推DP URAL 1031 Railway Tickets

题目传送门

/*
    简单递推DP：读题烦！在区间内的都更新一遍，dp[]初始化INF
    注意：s1与s2大小不一定，坑！
    详细解释：http://blog.csdn.net/kk303/article/details/6847948
*/
#include <cstdio>
#include <iostream>
#include <algorithm>
#include <cstring>
#include <string>
#include <queue>
using namespace std;

const int MAXN = 1e4 + 10;
const int INF = 0x3f3f3f3f;
int C[4], L[4];
int dp[MAXN], a[MAXN];

int main(void)        //URAL 1031 Railway Tickets
{
    //freopen ("Y.in", "r", stdin);

    while (scanf ("%d%d%d%d%d%d", &L[1], &L[2], &L[3], &C[1], &C[2], &C[3]) == 6)
    {
        int n;    scanf ("%d", &n);
        int s1, s2;
        scanf ("%d%d", &s1, &s2);
        if (s1 > s2)    swap (s1, s2);
        a[1] = 0;
        for (int i=2; i<=n; ++i)
        {
            scanf ("%d", &a[i]);    dp[i] = INF;
        }

        dp[s1] = 0;
        for (int i=s1+1; i<=s2; ++i)
        {
            for (int j=1; j<=3; ++j)
            {
                int k = i - 1;
                while (k >= s1)
                {
                    if (a[i] - a[k] > L[j])    break;
                    if (dp[i] > dp[k] + C[j])    dp[i] = dp[k] + C[j];
                    k--;
                }
            }
        }

        printf ("%d
", dp[s2]);
    }

    return 0;
}