Codeforces Round #276 (Div. 1)B（暴力）

B. Maximum Value

time limit per test

1 second

memory limit per test

256 megabytes

input

standard input

output

standard output

You are given a sequence a consisting of n integers. Find the maximum possible value of  (integer remainder of ai divided by aj), 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

3
3 4 5

output

2

題意：RT

思路：可以用nearest[i]表示離i最近且比i小的數

            然後對於每個數x，暴力遍歷x*2，x*3，.....,x*k，這時nearest數組派上用場了，直接由nearest[x*k]%x取最大值即可

#include 
#include 
#include 
#include 
#include 
#include 
using namespace std;

const int MAXN = 2000010;
int has[MAXN];
int nearest[MAXN];

int main()
{
    int n;
    scanf("%d",&n);
    for(int i=0;i=i){
                mx=max(mx,nearest[j]%i);
            }
        }
    }
    printf("%d\n",mx);
    return 0;
}