题解 | 画展布置

#include <iostream>
#include <algorithm>

using namespace std;

//注意精度，long long = int * int依旧可能会出现精度问题
int main() {
	int n, k;
	cin >> n >> k;
	long long* a = new long long[n];
	for (int i = 0; i < n; i++) {
		cin >> a[i];
	}
	sort(a, a + n);
	const long long INF = (long long) 1e11;
	long long ans = INF;
	long long big, small; 
	for (int i = 0; i < n - k + 1; i++) {
		big = a[i + k - 1] * a[i + k - 1];
		small = a[i] * a[i];
		ans = min(ans, big - small);
	}
	cout << ans << endl; 
}