A peak element is an element that is strictly greater than its neighbors.
Given a 0-indexed integer array nums, find a peak element, and return its index. If the array contains multiple peaks, return the index to any of the peaks.
You may imagine that nums[-1] = nums[n] = -∞. In other words, an element is always considered to be strictly greater than a neighbor that is outside the array.
You must write an algorithm that runs in O(log n) time.
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: 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.
Constraints:
1 <= nums.length <= 1000-231 <= nums[i] <= 231 - 1nums[i] != nums[i + 1] for all valid i.class Solution {
public int findPeakElement(int[] nums) {
int n = nums.length, lt = 0, rt = n - 1;
while (lt < rt) {
int mid = lt + (rt - lt) / 2;
if (nums[mid] < nums[mid + 1])
lt = mid + 1;
else
rt = mid;
}
return rt;
}
}