Number of Dice Rolls With Target Sum

class Solution {
public:
    int mod = 1e9+7;
    int solve(int dice, int faces, int target, vector<vector<long long>>& dp){
        if(target < 0)
            return 0;
        if(dice == 0 and target != 0)
            return 0;
        if(dice != 0 and target == 0)
            return 0;
        if(dice == 0 and target == 0)
            return 1;
        if(dp[dice][target] != -1)
            return dp[dice][target] % mod;

        long long ans = 0;
        for(int i = 1; i <= faces; i++){
            ans = ans + solve(dice - 1, faces, target - i, dp) % mod;
        }
        return dp[dice][target] = ans % mod;
    }
    int numRollsToTarget(int n, int k, int target) {
        vector<vector<long long>> dp(n + 1, vector<long long>(target + 1, -1));
        return solve(n, k, target, dp);
    }
};