hdu4648Magic Pen 6

http://acm.hdu.edu.cn/showproblem.php?pid=4648

求连续的一段和对m取余为0  若s[j]和s[i]对M的余数都相同 则相见就满足要求 找个最长的

#include <iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<stdlib.h>
using namespace std;
#define LL long long
#define N 100010
#define INF 0xfffffff
LL s[N];
int a[N],d1[N],d2[N];
int main()
{
    int i,j,n,m,k;
    while(cin>>n>>m)
    {
        memset(s,0,sizeof(s));
        LL sum=0;
        for(i = 1; i <= m ; i++)
        {
            d1[i] = -INF;
            d2[i] = INF;
        }
        int ans=0;
        for(i = 1; i <= n ; i++)
        {
            scanf("%d",&a[i]);
            sum+=a[i];
            s[i] = s[i-1]+a[i];
            k = s[i]%m;
            if(k<0) k+=m;
            if(k==0)
            ans = max(ans,i);
            d1[k] = max(d1[k],i);
            d2[k] = min(d2[k],i);
        }
        for(i = 1; i < m ; i++)
        ans = max(d1[i]-d2[i],ans);
        cout<<ans<<endl;
    }
    return 0;
}