河床

#include <iostream>
#include <algorithm>
#include <cstdio>
#include <map>
using namespace std;

int n, k, di[30005];
map<int,int> M;

int main(){
cin >> n >> k;
for (int i = 1; i <= n; ++i)
cin >> di[i];
int ans = 0;
for (int i = 1, j = 1; i <= n; ++i){
if (M.empty()){
++M[di[i]];
j = i+1;
}
while ((--M.end())->first - M.begin()->first <= k && j <= n) {
int mn = M.begin()->first;
int mx = (--M.end())->first;
if (di[j] - mn <= k && mx - di[j] <= k){
M[di[j]]++;
++j;
} else break;
}
if ((--M.end())->first - M.begin()->first<=k)
ans = max(ans, j - i);
--M[di[i]];
if (M[di[i]]==0)
M.erase(di[i]);
}
printf("%d\n",ans);
return 0;
}