package q162

// Important constraint: nums[i] != nums[i + 1]

func findPeakElement(nums []int) int {
	l, r := 0, len(nums)
	for l < r {
		m := (l + r) / 2

		lLower := m == 0 || nums[m-1] < nums[m]
		rLower := m == len(nums)-1 || nums[m+1] < nums[m]
		if lLower && rLower {
			return m
		}
		if !lLower { // left side is higher
			r = m
		} else {
			l = m + 1
		}
	}
	return -1
}

var _ = findPeakElement