rt，双指针通过记录

双指针code:

#include <bits/stdc++.h>
using namespace std;
int c[1000001];
int main() {
	int t, id;
	scanf("%d%d", &t, &id);
	while (t--) {
		int n;
		scanf("%d", &n);
		for (int i = 1; i <= n; i++)
			scanf("%d", c + i);
		if (id == 4) {
			if (n >= 4)
				puts("Yes");
			else
				puts("No");
			continue;
		}
		sort(c + 1, c + n + 1);
		int l = 2, r = n - 1, minl = c[1], maxn = c[n];
		while (r > l) {
			int x = maxn - c[l], y = c[r] - minl;
			if (x == y) {
				puts("Yes");
				goto out;
			} else if (x > y)
				l++;
			else
				r--;
		}
		puts("No");
		out:;
	}
	return 0;
}