LeetCode 1833: Maximum Ice Cream Bars

Problem Description

It is a sweltering summer day, and a boy wants to buy some ice cream bars.

At the store, there are n ice cream bars. You are given an array costs of length n, where costs[i] is the price of the i^th ice cream bar in coins. The boy initially has coins coins to spend, and he wants to buy as many ice cream bars as possible.

Note: The boy can buy the ice cream bars in any order.

Return the maximum number of ice cream bars the boy can buy with coins coins.

You must solve the problem by counting sort.

Example 1:

Input: costs = [1,3,2,4,1], coins = 7
Output: 4
Explanation: The boy can buy ice cream bars at indices 0,1,2,4 for a total price of 1 + 3 + 2 + 1 = 7.

Example 2:

Input: costs = [10,6,8,7,7,8], coins = 5
Output: 0
Explanation: The boy cannot afford any of the ice cream bars.

Example 3:

Input: costs = [1,6,3,1,2,5], coins = 20
Output: 6
Explanation: The boy can buy all the ice cream bars for a total price of 1 + 6 + 3 + 1 + 2 + 5 = 18.

Constraints:

costs.length == n
1 <= n <= 10⁵
1 <= costs[i] <= 10⁵
1 <= coins <= 10⁸

Difficulty: Medium

Tags: array, greedy, sorting, counting sort

Rating: 76.44%

Complexity Analysis

The solution has the following complexity characteristics:

Time Complexity: $O(n)$
Space Complexity: $O(n)$

where $n$ is the length of the costs array.

Note: This is an automated analysis and may not capture all edge cases or specific algorithmic optimizations.

Solution

Here’s my Python solution to this problem:

class Solution:
    def maxIceCream(self, costs: List[int], coins: int) -> int:
        minv, maxv = min(costs), max(costs)
        r = maxv - minv + 1

        cnt = [0] * r
        for c in costs:
            cnt[c-minv] += 1

        s = 0
        c = 0
        for i in range(r):
            while cnt[i] > 0 and s + (i + minv) < coins:
                s += i + minv
                c += 1
                cnt[i] -= 1
        
        return c