2888 Minimum Index Of A Valid Split

Minimum Index of a Valid Split

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 < n - 1
nums[0, ..., i], and nums[i + 1, ..., n - 1] have the same dominant element.

Here, nums[i, …, j] denotes the subarray of nums starting at index i and ending at index j, both ends being inclusive. Particularly, if j < i then nums[i, …, j] denotes an empty subarray.

Return the minimum index of a valid split. If no valid split exists, return -1.

 

Example 1:

**Input:** nums = [1,2,2,2]
**Output:** 2
**Explanation:** We can split the array at index 2 to obtain arrays [1,2,2] and [2]. 
In array [1,2,2], element 2 is dominant since it occurs twice in the array and 2 * 2 > 3. 
In array [2], element 2 is dominant since it occurs once in the array and 1 * 2 > 1.
Both [1,2,2] and [2] have the same dominant element as nums, so this is a valid split. 
It can be shown that index 2 is the minimum index of a valid split. 

Example 2:

**Input:** nums = [2,1,3,1,1,1,7,1,2,1]
**Output:** 4
**Explanation:** We can split the array at index 4 to obtain arrays [2,1,3,1,1] and [1,7,1,2,1].
In array [2,1,3,1,1], element 1 is dominant since it occurs thrice in the array and 3 * 2 > 5.
In array [1,7,1,2,1], element 1 is dominant since it occurs thrice in the array and 3 * 2 > 5.
Both [2,1,3,1,1] and [1,7,1,2,1] have the same dominant element as nums, so this is a valid split.
It can be shown that index 4 is the minimum index of a valid split.

Example 3:

**Input:** nums = [3,3,3,3,7,2,2]
**Output:** -1
**Explanation:** It can be shown that there is no valid split.

 

Constraints:

1 <= nums.length <= 105
1 <= nums[i] <= 109
nums has exactly one dominant element.

class Solution:
    def minimumIndex(self, nums: List[int]) -> int:
        dominant = -1
        count = -1
        temp = {}
        for k in nums:
            if k not in temp:
                temp[k] = 0
            temp[k] += 1
        
        for k in temp:
            if count < temp[k]:
                dominant = k
                count = temp[k]
        
        nc = 0
        for i, k in enumerate(nums):
            if k == dominant:
                nc += 1
            if nc > math.floor((i + 1) / 2) and count - nc > math.floor((len(nums) - i - 1) / 2):
                return i
        return -1