板子

#include"bits/stdc++.h"
using namespace std;

int n,k;
int dp[3000006][23];
int dp2[3000006][23];

 int query(int l,int r,int type)
{
   int ss=log2(r-l+1);
   if (type) return max(dp[l][ss],dp[r-(1<<ss)+1][ss]);  // r-(1<<ss)  !!+1
   else return min(dp2[l][ss],dp2[r-(1<<ss)+1][ss]);
}


 int check(int mid)
{
   for (int i=1;i+mid-1<=n;i++)
   {
      if (1ll*abs(query(i,i+mid-1,1)-query(i,i+mid-1,0))<=1LL*k)return 1; // i ,i+mid-1(!!<--)
   }
   return 0;
}
int main()
{
    //cout<<(int)pow(2,22);
    scanf("%d%d",&k,&n);
    for (int i=1;i<=n;i++)scanf("%d",&dp[i][0]),dp2[i][0]=dp[i][0];
    for (int i=1;i<=21;i++)
    {
       for (int j=1;j+(1<<i)-1<=n;j++)
       {
          dp[j][i]=max(dp[j+(1<<(i-1))][i-1],dp[j][i-1]);//j+(1<<(i-1))
          dp2[j][i]=min(dp2[j+(1<<(i-1))][i-1],dp2[j][i-1]);
       }
    }

   // cout<<query(4,7,1);

    int l=1,r=n; int ans ;
    while (l<=r)
    {
      int mid = l+r>>1;   //cout<<mid<<endl;
      if (check(mid))ans=mid,l=mid+1;else r=mid-1;
    }

    cout<<ans;
}