2780. Minimum Index of a Valid Split | Leetcode Daily - Python
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This video tackles LeetCode problem 2780, "Minimum Index of a Valid Split". We explore how to find the smallest index `i` that divides an integer array `nums` into two non-empty subarrays, `nums[0...i]` and `nums[i+1...n-1]`, such that both subarrays share the same dominant element. An element is dominant if it appears strictly more than half the times in its subarray. The video starts by explaining the problem with examples and reveals a crucial insight: the common dominant element in a valid split must be the dominant element of the original array. Leveraging this, we detail two approaches: first, using a hash map (like Python's `collections.Counter`) to find the dominant element and then checking potential splits, which runs in O(n) time and O(n) space. Second, we optimize the space complexity to O(1) using the Boyer-Moore Voting Algorithm to identify the dominant element candidate, followed by verifying its count and checking the splits, while maintaining O(n) time complexity. Both methods are explained clearly with Python code examples and complexity analysis.
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Solution Link:
https://leetcode.com/problems/minimum...
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