LeetCode 322 Coin Change

题目描述

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.

一句话题意

给你n种钱币，然后给你一个总数amount，这些钱币可以用无数次，问你用这些钱币组成这个amount，最少的数量是多少？如果不能组成返回-1.

解题思路

典型的背包型动态规划。。。

状态转移方程：

dp[j]=min(dp[j-coins[i]]+1,dp[j]);  0<j<=n,0<=i<=c;

过于基本就不多说什么了。