CF354C（思路+（左区间++，1+右区间--思想））

Vasya's got a birthday coming up and his mom decided to give him an array of positive integers a of length n.

Vasya thinks that an array's beauty is the greatest common divisor of all its elements. His mom, of course, wants to give him as beautiful an array as possible (with largest possible beauty). Unfortunately, the shop has only one array a left. On the plus side, the seller said that he could decrease some numbers in the array (no more than by k for each number).

The seller can obtain array b from array a if the following conditions hold: bi > 0; 0 ≤ ai - bi ≤ k for all 1 ≤ i ≤ n.

Help mom find the maximum possible beauty of the array she will give to Vasya (that seller can obtain).

Input

The first line contains two integers n and k (1 ≤ n ≤ 3·105; 1 ≤ k ≤ 106). The second line contains n integers ai (1 ≤ ai ≤ 106) — array a.

Output

In the single line print a single number — the maximum possible beauty of the resulting array.

Sample test(s)

input

6 1
3 6 10 12 13 16

output

3

input

5 3
8 21 52 15 77

output

7

Note

In the first sample we can obtain the array:

3 6 9 12 12 15

In the second sample we can obtain the next array:

7 21 49 14 77

法一：

//#pragma comment(linker, "/STACK:102400000")
#include<cstdlib>
#include<iostream>
#include<cstdio>
#include<cmath>
#include<cstring>
#include<algorithm>
#include<set>
#include<map>
#include<list>
#include<queue>
#include<stack>
#include<vector>
#include<ctime>
#define tree int o,int l,int r
#define lson o<<1,l,mid
#define rson o<<1|1,mid+1,r
#define lo o<<1
#define ro o<<1|1
#define pb push_back
#define mp make_pair
#define ULL unsigned long long
#define LL long long
#define inf 0x7fffffff
#define eps 1e-7
#define N 300009
using namespace std;
int m,n,T,t,k;
int a[N],minv;
int d[N*4],ncase;
int main()
{
#ifndef ONLINE_JUDGE
    freopen("ex.in","r",stdin);
#endif
    ncase=0;
    srand(time(0));
    while(scanf("%d%d",&n,&k)==2)
    {
        int l,r;
        minv=inf;
        for (int i=0; i<n; ++i )
        {
            scanf("%d",&a[i]);
            d[a[i]-k>=0?a[i]-k:0]++;
            d[a[i]+1]--;
            minv=min(minv,a[i]);
        }
        l=min(minv,k+1);
        r=minv;
        for (int i=1; i<1000001; ++i )
        d[i]=d[i-1]+d[i];
        int ans=l;
        for(int i=r;i>l;i--)
        {
            int cnt=0;
            for(int j=i;j<1000001;j+=i)
            cnt+=d[j];
            if(cnt==n)
            {
                ans=i;break;
            }
        }

        printf("%d\n",ans);
    }
    return 0;
}

法二：（别人的）

#include<cstdio>
#define min(x,y) (x<y?x:y)
using namespace std;
int main(){
    int n,k;
    scanf("%d%d",&n,&k);
    int a[n],g=0x7FFFFFFF;
    for (int i=0;i<n;i++){
        scanf("%d",&a[i]);
        g=min(g,a[i]);
    }
    int t,b;
    while (true){
        t=g;
        for (int i=0;i<n;i++){
            b=a[i]/g;
            if (!(b>0 && b*g>=a[i]-k))
                        g=a[i]/(b+1);//所有a[i]/g==b的g都不可行！（优化！）
        }
        if (t==g)break;
    }
    printf("%d\n",g);
    return 0;
}