Maximum Element After Decreasing and Rearranging — LeetCode 1846 Python Solution

The problem

You are given an array of positive integers arr. Perform some operations (possibly none) on arr so that it satisfies these conditions: The value of the first element in arr must be 1.

Example

Input

arr = [2,2,1,2,1]

Output

2

Explanation

We can satisfy the conditions by rearranging arr so it becomes [1,2,2,2,1].

Python solution

class Solution:
    def maximumElementAfterDecrementingAndRearranging(self, arr: List[int]) -> int:
        arr.sort()
        arr[0] = 1
        for i in range(1, len(arr)):
            d = max(0, arr[i] - arr[i - 1] - 1)
            arr[i] -= d
        return max(arr)

Complexity

Pattern: Greedy

Take the locally best option every time — when you can prove that never costs you later. LeetCode 1846. Maximum Element After Decreasing and Rearranging is filed here on both counts: the reference solution below belongs to the algorithm family this hub collects, and LeetCode tags it Greedy.

The greedy guide has the Python template for the pattern and the 346 LeetCode problems that use it.

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