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1760. Minimum Limit of Balls in a Bag

MediumOpen on LeetCodeProblem statement

Problem Statement

1760. Minimum Limit of Balls in a Bag

Medium


You are given an integer array nums where the ith bag contains nums[i] balls. You are also given an integer maxOperations.

You can perform the following operation at most maxOperations times:

Your penalty is the maximum number of balls in a bag. You want to minimize your penalty after the operations.

Return the minimum possible penalty after performing the operations.

 

Example 1:

Input: nums = [9], maxOperations = 2
Output: 3
Explanation: 
- Divide the bag with 9 balls into two bags of sizes 6 and 3. [9] -> [6,3].
- Divide the bag with 6 balls into two bags of sizes 3 and 3. [6,3] -> [3,3,3].
The bag with the most number of balls has 3 balls, so your penalty is 3 and you should return 3.

Example 2:

Input: nums = [2,4,8,2], maxOperations = 4
Output: 2
Explanation:
- Divide the bag with 8 balls into two bags of sizes 4 and 4. [2,4,8,2] -> [2,4,4,4,2].
- Divide the bag with 4 balls into two bags of sizes 2 and 2. [2,4,4,4,2] -> [2,2,2,4,4,2].
- Divide the bag with 4 balls into two bags of sizes 2 and 2. [2,2,2,4,4,2] -> [2,2,2,2,2,4,2].
- Divide the bag with 4 balls into two bags of sizes 2 and 2. [2,2,2,2,2,4,2] -> [2,2,2,2,2,2,2,2].
The bag with the most number of balls has 2 balls, so your penalty is 2, and you should return 2.

 

Constraints:

Java

Source file
class Solution {

    public int minimumSize(int[] nums, int maxOperations) {
        // Binary search bounds
        int left = 1;
        int right = 0;

        for (int num : nums) {
            right = Math.max(right, num);
        }

        // Perform binary search to find the optimal maxBallsInBag
        while (left < right) {
            int middle = (left + right) / 2;

            // Check if a valid distribution is possible with the current middle value
            if (isPossible(middle, nums, maxOperations)) {
                right = middle; // If possible, try a smaller value (shift right to middle)
            } else {
                left = middle + 1; // If not possible, try a larger value (shift left to middle + 1)
            }
        }

        // Return the smallest possible value for maxBallsInBag
        return left;
    }

    // Helper function to check if a distribution is possible for a given maxBallsInBag
    private boolean isPossible(
        int maxBallsInBag,
        int[] nums,
        int maxOperations
    ) {
        int totalOperations = 0;

        // Iterate through each bag in the array
        for (int num : nums) {
            // Calculate the number of operations needed to split this bag
            int operations = (int) Math.ceil(num / (double) maxBallsInBag) - 1;
            totalOperations += operations;

            // If total operations exceed maxOperations, return false
            if (totalOperations > maxOperations) {
                return false;
            }
        }

        // We can split the balls within the allowed operations, return true
        return true;
    }
}