Coin Change — LeetCode 322 Python Solution

The problem

You are given an integer array coins representing coins of different denominations and an integer amount representing a total amount of money. Return the fewest number of coins that you need to make up that amount.

Example

Input

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

Output

3

Explanation

11 = 5 + 5 + 1

Python solution

class Solution:
    def coinChange(self, coins: List[int], amount: int) -> int:
        m, n = len(coins), amount
        f = [[inf] * (n + 1) for _ in range(m + 1)]
        f[0][0] = 0
        for i, x in enumerate(coins, 1):
            for j in range(n + 1):
                f[i][j] = f[i - 1][j]
                if j >= x:
                    f[i][j] = min(f[i][j], f[i][j - x] + 1)
        return -1 if f[m][n] >= inf else f[m][n]

Complexity

Pattern: Breadth-First Search

Expand outward level by level, so the first time you arrive is the shortest way. LeetCode 322. Coin Change is filed here because LeetCode tags it Breadth-First Search, which is the vocabulary this hub collects.

The breadth-first search guide has the Python template for the pattern and the 233 LeetCode problems that use it.

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