code.go

// 162. Find Peak Element

// A peak element is an element that is greater than its neighbors.
// Given an input array nums, where nums[i] ≠ nums[i+1], find a peak element and return its index.
// The array may contain multiple peaks, in that case return the index to any one of the peaks is fine.
// You may imagine that nums[-1] = nums[n] = -∞.

// Example 1:
// Input: nums = [1,2,3,1]
// Output: 2
// Explanation: 3 is a peak element and your function should return the index number 2.

// Example 2:
// Input: nums = [1,2,1,3,5,6,4]
// Output: 1 or 5
// Explanation: Your function can return either index number 1 where the peak element is 2, or index number 5 where the peak element is 6.

// Note: Your solution should be in logarithmic complexity.

package leetcode

func findPeakElement(nums []int) int {
	lo, hi := 0, len(nums)-1
	for lo < hi {
		mid := lo + (hi-lo)/2
		if nums[mid] > nums[mid+1] {
			hi = mid
		} else {
			lo = mid + 1
		}
	}
	return lo
}