思路:每一次求取一个范围,然后判断之后的小方格是否满足范围。对于最后和第一个方格已经取定,需要特殊判断,细节见代码。
Code:
#include<iostream>
#include<string>
#include<map>
#include<algorithm>
#include<memory.h>
#include<cmath>
#define pii pair<int,int>
#define FAST ios::sync_with_stdio(false),cin.tie(0),cout.tie(0)
using namespace std;
typedef long long ll;
const int Max = 1e6 + 5;
int Mod = 1e9 + 7;
int h[Max];
int main()
{
int t;cin >> t;
while (t--)
{
int n, k;cin >> n >> k;
for (int i = 1;i <= n;i++)cin >> h[i];
int l = h[1], r = h[1];
int f = 1;
for (int i = 2;i <= n-1;i++)
{
if (h[i] >= h[i - 1])
{
if (h[i] >= r + k) {
f = 0;break; }
l = h[i], r = min(h[i] + k-1, r + k - 1);
}
else
{
if (h[i] + k+k-1 <= l) {
f = 0;break; }
r = h[i] + k - 1, l = max(h[i], l - k + 1);
}
}
if (h[n] + k <= l || h[n] >= r + k)f = 0;
if (f)cout << "YES" << endl;
else cout << "NO" << endl;
}
}