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1247. Decrease Elements To Make Array Zigzag

My accepted Python solution to LeetCode problem 1247, Decrease Elements To Make Array Zigzag, running in 3ms.

  • Difficulty: Medium
  • Python
  • Runtime 3ms
  • Memory 17.6MB

Read the problem on LeetCode View on GitHub

The problem statement is LeetCode’s and stays on their site. What follows is my accepted solution.

Python

Accepted on LeetCode — runtime 3ms, memory 17.6MB, accepted 2026-01-02.

python
class Solution:
    def movesToMakeZigzag(self, nums: List[int]) -> int:
        def helper(parity):
            # Make elements at parity indices smaller than neighbors
            moves = 0
            for i in range(parity, len(nums), 2):
                left = nums[i - 1] if i > 0 else float('inf')
                right = nums[i + 1] if i < len(nums) - 1 else float('inf')
                target = min(left, right) - 1
                if nums[i] > target:
                    moves += nums[i] - target
            return moves
        
        # Either make even indices smaller or odd indices smaller
        return min(helper(0), helper(1))

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