# 2780. Minimum Index of a Valid Split from collections import Counter """ an element 'x' of an integer array 'arr' of length 'm' is dominant if more than half the elements of 'arr' have a value of 'x'. you are given a 0-indexed integer array 'nums' of length 'n' with one dominant element. you can split 'nums' at an index 'i' into two arrays 'nums[0, ..., i]' and 'nums[i + 1, ..., n - 1]', but the split is only valid if '0 <= i < - 1' and the two arrays have the same dominant element. return the minimum index of a valid split. if no split exists, return -1. """ class Solution(object): def minimumIndex(self, nums): """ :type nums: List[int] :rtype: int """ dominant, cnt = max(Counter(nums).items(), key=lambda x: x[1]) left, split = 0, 2 * cnt - len(nums) if split < 2: return -1 for i, j in enumerate(nums): left += 2 * (j == dominant) if 1 < left - i <= split: return i if __name__ == "__main__": obj = Solution() print(obj.minimumIndex(nums=[1, 2, 2, 2])) print(obj.minimumIndex(nums=[2, 1, 3, 1, 1, 1, 7, 1, 2, 1])) print(obj.minimumIndex(nums=[3, 3, 3, 3, 7, 2, 2]))