A peak element is an element that is strictly greater than its neighbors.
Given an 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] = -∞.
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 - 1
- nums[i] != nums[i + 1] for all valid i.
class Solution {
public int findPeakElement(int[] nums) {
int low = 0;
int high = nums.length-1;
while(low<high){
int mid1 = (low+high)/2;
int mid2 = mid1+1;
if(nums[mid1] < nums[mid2]){
low = mid2;
}else{
high = mid1;
}
}
return low;
}
}