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,,sizeof(s));
         LL sum=;
         for(i = ; i <= m ; i++)
         {
             d1[i] = -INF;
             d2[i] = INF;
         }
         int ans=;
         for(i = ; i <= n ; i++)
         {
             scanf("%d",&a[i]);
             sum+=a[i];
             s[i] = s[i-]+a[i];
             k = s[i]%m;
             if(k<) k+=m;
             if(k==)
             ans = max(ans,i);
             d1[k] = max(d1[k],i);
             d2[k] = min(d2[k],i);
         }
         for(i = ; i < m ; i++)
         ans = max(d1[i]-d2[i],ans);
         cout<<ans<<endl;
     }
     return ;
 }