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Problem Brief

Find Peak Element

PHONE SCREEN

Based on the source, the other question being asked was -

Given an array of positive integers and target, return True if sum of continues array equal to target.

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.

1Example 1

Input
nums = [1,2,3,1]
Output
2
Explanation

3 is a peak element and your function should return the index number 2.

2Example 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

Limits and guarantees your solution can rely on.

  • 1 <= nums.length <= 1000
  • -2^31 <= nums[i] <= 2^31 - 1
  • nums[i] != nums[i + 1] for all valid i.
public int findPeakElement(int[] nums) {
  // write your code here (You may want to refer to LC 162)
}
Input

nums

[1,2,3,1]

Output

2

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