B.MaximumValue（CodeforcesRound#276(div1)_html/css_WEB-ITnose

time limit per test

memory limit per test

input

output

You are given a sequence a consisting of n integers. Find the maximum possible value of (integer remainder of ai divided byaj), where 1?≤?i,?j?≤?n and ai?≥?aj.

Input

The first line contains integer n ? the length of the sequence (1?≤?n?≤?2·105).

The second line contains n space-separated integers ai (1?≤?ai?≤?106).

Output

Print the answer to the problem.

Sample test(s)

input

33 4 5

output

找a[i]

由于ai<1000000;可以hash搞，如果一个点不存在，记录比它小的最大值。

至于找最大模后的值，取a[i]==i也就是这个点存在，取模后的最大值肯定i+1+k*i,这样每次增加i查询，

查到离最大值最近的值。

代码：

#include #include #include #include using namespace std;const int maxn=2000000+100;int a[maxn];int main(){    int n;    scanf("%d",&n);    int x;    for(int i=0;ians&&a[j]>i)                ans=a[j]%i;            }        }    }    printf("%d\n",ans);    return 0;}