Dice throw

class Solution {
    static int noOfWays(int m, int n, int x) {
        if (n * m < x)
            return 0;

        int dp[][] = new int[n + 1][x + 1];

        for (int i = 0; i <= n; i++) {
            for (int j = 0; j <= x; j++)
                dp[i][j] = -1;
        }

        return solve(m, n, x, dp);
    }

    static int solve(int m, int n, int x, int dp[][]) {
        if (n == 0 && x == 0)
            return 1;

        if (n == 0)
            return 0;

        if (dp[n][x] != -1)
            return dp[n][x];

        int ans = 0;
        for (int j = 1; j <= m; j++) {
            if (x - j >= 0)
                ans += solve(m, n - 1, x - j, dp);
        }

        return dp[n][x] = ans;
    }
};