LeetCode/go/minimum-index-of-a-valid-split.go

package main

func minimumIndex(nums []int) int {
	majorityElement := func() int {
		dom, count := nums[0], 0

		for _, x := range nums {
			if x == dom {
				count++
			} else {
				count--
			}

			if count == 0 {
				dom = x
				count = 1
			}
		}

		return dom
	}
	dom := majorityElement()

	// get frequency
	domCount := 0
	for _, x := range nums {
		if x == dom {
			domCount++
		}
	}

	// Check for split
	count := 0
	for i, x := range nums {
		if x == dom {
			count++
		}

		remaining := domCount - count
		if 2*count > i+1 && 2*remaining > len(nums)-i-1 {
			return i
		}
	}

	// couldn't find a valid split
	return -1
}