LeetCode 322: Coin Change, Deriving Unbounded Knapsack DP from Smaller Amounts
Problem Requirements You are given an integer array coins, where coins[i] is a coin denomination, and a non-negative integer amount. The goal is to make a total exactly equal to amount. You may use each denomination any number of times. Return the minimum number of coins needed to make amount. If the amount cannot be made, return -1. If amount = 0, no coins are needed, so the answer is 0. The constraints are 1 <= coins.length <= 12, 1 <= coins[i] <= 2^31 - 1, and 0 <= amount <= 10^4. All coin denominations are distinct. ...