Package g0801_0900.s0852_peak_index_in_a_mountain_array

Class Solution

  • All Implemented Interfaces:
    
public final class Solution

    852 - Peak Index in a Mountain Array\.

    Medium

    An array arr a mountain if the following properties hold:

    • arr.length >= 3

    • There exists some i with 0 < i < arr.length - 1 such that:

    Given a mountain array arr, return the index i such that arr[0] < arr[1] < ... < arr[i - 1] < arr[i] > arr[i + 1] > ... > arr[arr.length - 1].

    You must solve it in O(log(arr.length)) time complexity.

    Example 1:

    Input: arr = 0,1,0

    Output: 1

    Example 2:

    Input: arr = 0,2,1,0

    Output: 1

    Example 3:

    Input: arr = 0,10,5,2

    Output: 1

    Constraints:

    • <code>3 <= arr.length <= 10<sup>5</sup></code>

    • <code>0 <= arri<= 10<sup>6</sup></code>

    • arr is guaranteed to be a mountain array.

    • Nested Class Summary

      Nested Classes 
      Modifier and Type Class Description

    • Field Summary

      Fields 
      Modifier and Type Field Description

    • Constructor Summary

      Constructors 
      Constructor Description
      Solution()

    • Enum Constant Summary

      Enum Constants 
      Enum Constant Description

    • Method Summary

      Modifier and Type Method Description
      final Integer peakIndexInMountainArray(IntArray arr)

      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait