322.零钱兑换

```

class Solution {
    public int coinChange(int[] coins, int amount) {
        int[] dp = new int[amount+1];
        int max = amount+1;
        Arrays.fill(dp,max);
        dp[0] = 0;
        for(int i = 1; i <= amount; i++){
            for(int j = 0; j < coins.length; j++){
                if(coins[j] <= i){
                    dp[i] = Math.min(dp[i],dp[i-coins[j]]+1);
                }
            }
        }
        return dp[amount] > amount ? -1 : dp[amount];
    }
}