标签：des blog http io ar os sp for strong
Description
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 Input
3
3 4 5
2
#include<iostream>
#include<cstdio>
#include<cstring>
#include<string>
#include<cmath>
#include<cstdlib>
#include<algorithm>
#include<queue>
#include<vector>
#include<set>
using namespace std;
int a[200010];
inline int mymax(int a,int b){
return a > b? a: b;
}
inline int bin_search(int l,int r,int val)//二分查找小于val的最大值
{
int mid;
while(l<=r){
mid=(l+r)>>1;
if(a[mid]==val) return mid-1;
else if(a[mid]>val) r=mid-1;
else l=mid+1;
}
return r;
}
int main()
{
int n;
while(~scanf("%d",&n)){
for(int i=0;i<n;i++)
scanf("%d",&a[i]);
sort(a,a+n);
int mmax = 0;
for(int i=0;i<n-1;i++){
if(a[i]!=a[i-1]){//剪枝。如果之前出现过了就不用查了；
int tmp=a[i]+a[i];
while(tmp<=a[n-1]){
int pos=bin_search(0,n-1,tmp);
mmax = mymax(mmax,a[pos]%a[i]);
tmp+=a[i];
}
mmax =mymax(mmax,a[n-1]%a[i]);
}
}
printf("%d\n",mmax);
}
return 0;
}
标签：des blog http io ar os sp for strong
原文地址：http://www.cnblogs.com/a972290869/p/4110158.html
