322. Coin Change

思路：动态规划

class Solution {
public:
    int coinChange(vector<int>& coins, int amount) {
        //定义变量和初始化
        sort(coins.begin(),coins.end(),less<int>());
        int len=coins.size();
        
        vector<int> dp(max(amount,len)+1,-1);dp[0]=0;
        for(int i=1;i<=amount;i++){
            for(int j=0;j<len;j++){
                if(i-coins[j]>=0&&dp[i-coins[j]]!=-1) {
                    if(dp[i]==-1||dp[i]>dp[i-coins[j]]+1) dp[i]=dp[i-coins[j]]+1;
                    
                }
            }
        }
        
        //for(int i=1;i<=amount;i++){cout<<dp[i]<<endl;}
        return dp[amount];
    }
};