LeetCode 2010: The Number of Seniors and Juniors to Join the Company II Solution

class Solution {
    public int numberOfOptions(int num, int[] seniors, int[] juniors, int target) {
        long[][] dp = new long[num + 1][num + 1];
        dp[0][0] = 1;
        
        for (int senior : seniors) {
            for (int i = num; i >= 0; i--) {
                for (int j = num; j >= 0; j--) {
                    if (i - 1 >= 0 && j >= 0) {
                        dp[i][j] += dp[i - 1][j];
                    }
                }
            }
        }
        
        for (int junior : juniors) {
            for (int i = num; i >= 0; i--) {
                for (int j = num; j >= 0; j--) {
                    if (i >= 0 && j - 1 >= 0) {
                        dp[i][j] += dp[i][j - 1];
                    }
                }
            }
        }
        
        long result = 0;
        for (int i = 0; i <= num; i++) {
            for (int j = 0; j <= num; j++) {
                if (seniors.length * i - juniors.length * j >= target) {
                    result += dp[i][j];
                }
            }
        }
        
        return (int) (result % 1000000007);
    }
}