POJ 1678 I Love this Game!#dp博弈

http://poj.org/problem?id=1678

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;

const int INF=10e8;
int n,a,b,p[10005],dp[10005];

int dfs(int x)
{
    if(dp[x]!=-INF)
        return dp[x];

    int ans=INF;
    for(int i=x+1;i<n;i++)
        if(p[i]-p[x]>=a&&p[i]-p[x]<=b)//对方要尽量取差值大的，那么要得到差值尽可能小的
            ans=min(ans,p[x]-dfs(i)); //== ans=max(ans,dfs(i)); ans=p[x]-ans;
    if(ans==INF)
        return dp[x]=p[x];
    return dp[x]=ans;
}

int op()
{
    int ans=-INF;
    for(int i=0;i<n;i++)
        if(p[i]>=a&&p[i]<=b)
            ans=max(ans,dfs(i));
    return ans==-INF?0:ans;
}

int main()
{
    int t;
    scanf("%d",&t);
    while(t--)
    {
        scanf("%d%d%d",&n,&a,&b);
        for(int i=0;i<n;i++)
        {
            scanf("%d",&p[i]);
            dp[i]=-INF;
        }
        sort(p,p+n);
        printf("%d\n",op());
    }
    return 0;
}