C++

$\color{#cc33ff}{— > 算法基础课题解}$

$图解：$

#include<iostream>

using namespace std;

const int N = 2010, mod = 1e9 + 7;

int c[N][N];

void init() {
    for (int i = 0; i < N; i ++)
        for (int j = 0; j <= i; j ++)
            if (!j) c[i][j] = 1;
            else c[i][j] = (c[i - 1][j] + c[i - 1][j - 1]) % mod;
}

int main() {
    init();

    int n; cin >> n;
    while (n --) {
        int a, b; cin >> a >> b;
        cout << c[a][b] << endl;
    }

    return 0;
}