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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
33 4 5
output
题意：RT
思路：可以用nearest[i]表示离i最近且比i小的数
然后对于每个数x，暴力遍历x*2，x*3，.....,x*k，这时nearest数组派上用场了，直接由nearest[x*k]%x取最大值即可