Recursion & DP Target: 15s
Unbounded knapsack DP: iterate coins outer, amounts inner. Classic DP problem.
dp = [float('inf')] * (amount + 1)
dp[0] = 0
for coin in coins:
for x in range(coin, amount + 1):
dp[x] = min(dp[x], dp[x - coin] + 1)Type it from memory. Go.