Coin Change

322. Coin Change

Total Accepted: 4182 Total Submissions: 16210 Difficulty: Medium

You are given coins of different denominations and a total amount of money amount. Write a function to compute the fewest number of coins that you need to make up that amount. If that amount of money cannot be made up by any combination of the coins, return -1.

Example 1:
coins = [1, 2, 5], amount = 11
return 3 (11 = 5 + 5 + 1)

Example 2:
coins = [2], amount = 3
return -1.

Note:
You may assume that you have an infinite number of each kind of coin.

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Dynamic Programming

class Solution {
public:
    int coinChange(vector<int>& coins, int amount) {
        if(amount == 0) return 0;
        vector<int> dp(amount+1,0);
        int coins_size = coins.size();
        for(int i=0;i<=amount;i++){
            int  cur_min    = INT_MAX;
            bool has_found  = false;
            for(int j=0;j<coins_size;j++){
                if(coins[j]==i){
                    cur_min   = 0;
                    has_found = true;
                    break;
                }
                if(coins[j]< i && dp[i-coins[j]]!=-1){
                    cur_min   = min(dp[i-coins[j]],cur_min);
                    has_found = true;
                }
            }
            dp[i] = has_found ? cur_min+1 : -1;
        }
        return dp.back();
    }
};