首页 > 代码库 > Codesforces 485D Maximum Value

Codesforces 485D Maximum Value

                                                  D. Maximum Value
 

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
3
3 4 5
output
2

 

 

给出 n 个数 a[0] ~ a[n-1] ,要你找出 a[i] % a[j] 最大.

处理一个数组x[i]表示 1~i 离i最近的数是什么。就可以过了。

 

#include <bits/stdc++.h>using namespace std;typedef long long LL;const int mod = (1e9+7);const int N = 2000010;bool num[N];int x[N] , a;int main(){    int n ;    cin >> n ;    for( int i = 0 ; i < n ; ++i ) {        cin >> a;        num[a] = 1 ;    }        for( int i = 0 ; i <= 2e6 ; ++i ){        if( num[i] )x[i] = i ;        else x[i] = x[i-1] ;    }    int res = 0  ;    for( int i = 1 ; i <= 1e6 ; ++i ) if( num[i] ){         for( int j = 2 * i ; j <= 2e6 ; j += i ) {            res = max( res , ( x[j-1] ) % i );        }    }    cout << res << endl;}
View Code

 

 

 

Codesforces 485D Maximum Value