Leetcode 322. Coin Change

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.

Dynamic Programming 解决 coin exchange problem,找最小值，利用Dynamic programming 解决问题

public class Solution {    public int coinChange(int[] coins, int amount) {        int[] dp = new int[amount + 1];        // int max = 0X        for(int i = 1; i <= amount; i++){            dp[i] = Integer.MAX_VALUE;        }                dp[0] = 0;        for(int i = 0; i <= amount; i++){            for(int j = 0; j < coins.length; j++){                if (dp[i] != Integer.MAX_VALUE && i + coins[j] <= amount)                    dp[i + coins[j]] = Math.min(dp[i + coins[j]],dp[i] + 1);             }        }        return dp[amount] == Integer.MAX_VALUE? -1:dp[amount];    }}

这道题还有一个变形

就是数有多少种找钱的方式，看这里，recursive的题很容易懂，然后DP没看懂

http://www.geeksforgeeks.org/dynamic-programming-set-7-coin-change/