Find peak element

Array Binary Search

46.8% acceptance

Jan 12, 2026

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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.

Solution

Rust

Time O(n log n)

Space O(1)

LeetCode

solution.rs

impl Solution {
  pub fn find_peak_element(nums: Vec<i32>) -> i32 {
    let mut left = 0;
    let mut right = nums.len() - 1;
    
    while left < right {
      let mid = left + (right - left) / 2;
      if nums[mid] > nums[mid + 1] {
        right = mid;
      } else {
        left = mid + 1;
      }
    }
    
    left as i32
  }
}