leetcode518

 1 class Solution {
 2     public int change(int amount, int[] coins) {
 3         if (amount == 0) {
 4             return 1;
 5         }
 6         if(coins == null || coins.length == 0){
 7             return 0;
 8         }
 9         int[] dp = new int[amount + 1];
10         dp[0] = 1;
11         for (int coin : coins) {
12             for (int i = coin; i <= amount; i++) {
13                 dp[i] += dp[i - coin];
14             }
15         }
16         return dp[amount];
17     }
18 }

对比leetcode322：

 1 public class Solution {
 2     public int coinChange(int[] coins, int amount) {
 3         if (amount == 0) return 0;
 4         int[] dp = new int[amount + 1];
 5         dp[0] = 0;
 6         for (int i = 1;i <= amount ;i++ ) {
 7             dp[i] = Integer.MAX_VALUE;
 8             for(int k :coins) {
 9                 if(i>=k && dp[i-k] != Integer.MAX_VALUE) {
10                     dp[i] = Math.min(dp[i-k] + 1,dp[i]);
11                 }
12             }
13         }
14         if(dp[amount]<Integer.MAX_VALUE && dp[amount] > 0) {
15             return dp[amount];
16         } else {
17             return -1;
18         }
19 
20     }
21 }