Problem Description
There is a sequence of integers. Your task is to find the longest subsequence that satisfies the following condition: the difference between the maximum element and the minimum element of the subsequence is no smaller than m and no larger than k.
 
 


Input
There are multiple test cases.
For each test case, the first line has three integers, n, m and k. n is the length of the sequence and is in the range [1, 100000]. m and k are in the range [0, 1000000]. The second line has n integers, which are all in the range [0, 1000000].
Proceed to the end of file.
 
 


Output
For each test case, print the length of the subsequence on a single line.
 
 


Sample Input
5 0 0 1 1 1 1 1 5 0 3 1 2 3 4 5
 
 


Sample Output

5 4

 單調佇列。
用兩個單調佇列維護最大值和最小值。

#include<stdio.h>
#include<string.h>
#include<math.h>
#include<iostream>
#include<algorithm>
#include<queue>
#include<stack>
using namespace std;
#define ll long long
#define getMax(a,b) a>b?a:b
#define getMin(a,b) a<b?a:b
const int N=1e+5+5;
int q[N],p[N],h1,h2,r1,r2;
int a[N];
int main()
{
    int n,m,k,i;
    while (~scanf("%d%d%d",&n,&m,&k))
        {
            h1=h2=r1=r2=0;
            int ans=0,cur=1;
            for (i=1;i<=n;i++)
            {
                scanf("%d",&a[i]);
            while (h1<r1&&a[q[r1-1]]<a[i])  //遞減
                r1--;
            q[r1++]=i;
            while (h2<r2&&a[p[r2-1]]>a[i])  //遞增
                r2--;
            p[r2++]=i;
            while (h1<r1&&h2<r2&&a[q[h1]]-a[p[h2]]>k)  //選擇下標小的
            {
                if (q[h1]<p[h2])
                    cur=q[h1++]+1;
                else
                    cur=p[h2++]+1;
            }
            if (h1<r1&&h2<r2&&a[q[h1]]-a[p[h2]]>=m)
                if (ans<i-cur+1)
                ans=i-cur+1;
            }
            printf("%d\n",ans);
        }
    return 0;
}