Coin change leetcode

class Solution {
public:
    int dp[1000000];
    int inf = 99999999;
    int coinChange(vector<int>& coins, int amount) {
        memset(dp, -1, sizeof(dp));
        sort(coins.begin(), coins.end());

        int ans = solve(coins, amount);
        if(ans >= inf){
            ans = -1;
        }
        return ans;
    }

    int solve(vector<int>& coins, int amount) {

        if(amount <= 0){
            return 0;
        }

        if(dp[amount] != -1) return dp[amount];
        int ret = inf, temp;

        for(int i = coins.size() - 1; i >=0; i--){
            if(amount >= coins[i]){
                temp = solve(coins, amount - coins[i]);
                ret = min(ret, temp);
            }
        }
        return dp[amount] = 1 + ret;
    }




};