Medium

Quiz

#518 Coin Change II

APPROACH

You are given an integer array coins of available denominations and an integer amount as a monetary target. With an unlimited supply of each coin type, return the total number of distinct combinations that sum exactly to amount. Return 0 if no valid combination exists. The result is guaranteed to fit within a signed 32-bit integer.

Example 1:

Input: amount = 5, coins = [1,2,5]

Output: 4

Explanation: there are four ways to make up the amount:

5=5

5=2+2+1

5=2+1+1+1

5=1+1+1+1+1

Example 2:

Input: amount = 3, coins = [2]

Output: 0

Explanation: the amount of 3 cannot be made up just with coins of 2.

Example 3:

Input: amount = 10, coins = [10]

Output: 1

1 of 4

1:00

What is the optimal approach for this problem?