cf460c present

#include <cmath>
#include <cstring>
#include <cstdio>
#include<algorithm>
using namespace std;
long long N, M, W;
long long h[100010], dis[100010];
bool (long long x)
{
    long long sum = 0, ans = 0;
    for (int i = 1; i <= N;i++)
    {
        sum += dis[i];
        if(sum<x)
        {
            ans += x - sum;
            dis[i] += x - sum;
            if(i+W<=N)
                dis[i + W] -= x - sum;//开始这个点写成了i+W+1，WA了后来知道这个和以前给的左右区间是有区别的。 
            sum += x - sum;
        }
    }
    return ans <= M;
}
int main()
{
    cin >> N >> M >> W;
    long long l = 9999999999999, r = -1;
    for (int i = 1; i <= N;i++)
    {
        cin >> h[i];
        dis[i] = h[i] - h[i - 1];
        l = min(l, h[i]);
        r = max(r, h[i]);
    }
    r += M;
    long long ans;
    while(l<=r)
    {
        long long mid = l + r >> 1;
        if(check(mid))
        {
            l = mid+1;
            ans=mid;
        }
        else r = mid-1;
        for (int i = 1; i <= N;i++)
        {
            dis[i] = h[i] - h[i - 1];
        }
    }
    cout << ans << endl;
}