2780. Minimum Index of a Valid Split

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1. Because we split array into 2 sub array, the findCount must >= 2/n (arr element count)
2. Just compare current left subarray, and right subarray if they meet requirement.

class Solution:
    def minimumIndex(self, nums: List[int]) -> int:
        
        n = len(nums)
        
        findCount = ceil(float(n) / 2)
        
        c = Counter(nums)
        
        for key, value in list(c.items()):
            if value < findCount:
                c.pop(key)
                
        M = defaultdict(int)
        
        for i in range(n):
            if nums[i] not in c:
                continue

            M[nums[i]] += 1
            c[nums[i]] -= 1
            
            if 2 * M[nums[i]] >  i + 1 and 2 * c[nums[i]] > n - i - 1:
                return i
            
        return -1