孙老板的代码 （dp），能看懂就看看吧 ，没准以后可能大概也许或许会来注释

#include <bits/stdc++.h>
using namespace std;
const int maxn = 1005;
int a[maxn], b[maxn], dp[maxn][maxn][2];
int main(){
	//freopen("pass.in","r",stdin);
	//freopen("pass.out","w",stdout);
	int n, m, k, q;
	cin >> n >> m >> k >> q;
	for(int i = 1; i <= n; i++){
		cin >> a[i];
	}
	for(int i = 1; i <= n; i++){
		cin >> b[i];
	}
	a[n+1] = a[n];
	b[n+1] = b[n];
	memset(dp, 0x3f, sizeof dp);
	dp[0][0][0] = 0;
	dp[0][0][1] = 1;
	for(int step = 0; step <= 2 * n; step++){
		for(int j = 0; j <= min(n, step); j++){
			int i = step - j;
			if(i > n)	continue;
			for(int k = 0, r = 0; r <= 3; k++, r++){ // 枚举第三维时，在原地转移 4 次，这样 0 1 都被互相求 min
				k = r % 2;
				if(dp[i][j][k] >= 1e9)	continue;
				if(abs(a[i] - b[j]) <= q)
					dp[i][j][k^1] = min(dp[i][j][k^1], dp[i][j][k] + 1);
				if(k == 0){
					dp[i+1][j][k] = min(dp[i+1][j][k], dp[i][j][k]);
					if(b[j+1] - b[j] <= m){
						dp[i][j+1][k] = min(dp[i][j+1][k], dp[i][j][k]);
					}
				}else{
					dp[i][j+1][k] = min(dp[i][j+1][k], dp[i][j][k]);
					if(a[i+1] - a[i] <= m){
						dp[i+1][j][k] = min(dp[i+1][j][k], dp[i][j][k]);
					}
				}
			}
		}
		
	}
	cout << min(dp[n][n][0], dp[n][n][1])<< endl;
	return 0;
}