感觉没有太大问题，RE 的，应该不是公式写错了，求助 $\texttt qw\texttt q$

#include <bits/stdc++.h>
using namespace std;
const long long p = 1e9 + 7;
long long t, n, m, k;

long long f(long long n, long long m) {
	long long a = 1;
	while (m) {
		if (m & 1)
			a = n * a % p;
		m >>= 1;
		n = n * n % p;
	}
	return a % p;
}

long long C(int n, int m) {
	long long a = 1, b = 1;
	for (int i = n, cnt = 1; cnt <= m; i--, cnt++)
		a *= i;
	for (int i = m; i; i--)
		b *= i;
	return a / b;
}

int main() {
	cin >> t;
	while (t--) {
		cin >> n >> m >> k;
		if (k > n || m < 2 * k)
			cout << 0 << endl;
		else
			cout << C(n, k) *C(n - k, m - 2 * k) % p *f(2, m - 2 * k) % p;
	}
	return 0;
}