How should I practice Coin Change?

Start by reading the full statement, solve the visible examples, then compare the pattern against related Grubhub phone screen problems in FastPrep.

Is Coin Change associated with Grubhub?

FastPrep tags this as a Grubhub phone screen coding practice problem when the problem catalog has that company and stage context.

Problem · Array

Coin Change

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Problem statement

You are given an array coins of distinct positive coin denominations and a nonnegative integer amount.

You have an unlimited supply of every denomination. Return the minimum number of coins needed to make exactly amount. If no combination can make the amount, return -1.

An amount of 0 requires 0 coins.

Function

coinChange(coins: int[], amount: int) → int

Examples

Example 1

coins = [1,2,5]amount = 11return = 3

Two coins of denomination 5 and one coin of denomination 1 make 11 with three coins.

Example 2

coins = [2]amount = 3return = -1

No number of coins with denomination 2 can make the odd amount 3.

Example 3

coins = [1]amount = 0return = 0

The empty selection makes amount 0.

Constraints

1 <= coins.length <= 12.
1 <= coins[i] <= 2^31 - 1.
All denominations are distinct.
0 <= amount <= 10000.