Package g1901_2000.s1964_find_the_longest_valid_obstacle_course_at_each_position

Class Solution

java.lang.Object
g1901_2000.s1964_find_the_longest_valid_obstacle_course_at_each_position.Solution
public class Solution extends java.lang.Object
1964 - Find the Longest Valid Obstacle Course at Each Position.

Hard

You want to build some obstacle courses. You are given a 0-indexed integer array obstacles of length n, where obstacles[i] describes the height of the ith obstacle.

For every index i between 0 and n - 1 ( inclusive ), find the length of the longest obstacle course in obstacles such that:

  • You choose any number of obstacles between 0 and i inclusive.
  • You must include the ith obstacle in the course.
  • You must put the chosen obstacles in the same order as they appear in obstacles.
  • Every obstacle (except the first) is taller than or the same height as the obstacle immediately before it.

Return an array ans of length n, where ans[i] is the length of the longest obstacle course for index i as described above.

Example 1:

Input: obstacles = [1,2,3,2]

Output: [1,2,3,3]

Explanation: The longest valid obstacle course at each position is:

  • i = 0: [1], [1] has length 1.

  • i = 1: [1,2], [1,2] has length 2.

  • i = 2: [1,2,3], [1,2,3] has length 3.

  • i = 3: [1,2,3,2], [1,2,2] has length 3.

Example 2:

Input: obstacles = [2,2,1]

Output: [1,2,1]

Explanation: The longest valid obstacle course at each position is:

  • i = 0: [2], [2] has length 1.

  • i = 1: [2,2], [2,2] has length 2.

  • i = 2: [2,2,1], [1] has length 1.

Example 3:

Input: obstacles = [3,1,5,6,4,2]

Output: [1,1,2,3,2,2]

Explanation: The longest valid obstacle course at each position is:

  • i = 0: [3], [3] has length 1.

  • i = 1: [3,1], [1] has length 1.

  • i = 2: [3,1,5], [3,5] has length 2. [1,5] is also valid.

  • i = 3: [3,1,5,6], [3,5,6] has length 3. [1,5,6] is also valid.

  • i = 4: [3,1,5,6,4], [3,4] has length 2. [1,4] is also valid.

  • i = 5: [3,1,5,6,4,2], [1,2] has length 2.

Constraints:

  • n == obstacles.length
  • 1 <= n <= 105
  • 1 <= obstacles[i] <= 107

  • Constructor Summary

    Constructors
    Constructor
    Description
    Solution()
     

  • Method Summary

    Modifier and Type
    Method
    Description
    int[]
    longestObstacleCourseAtEachPosition(int[] obstacles)
     

    Methods inherited from class java.lang.Object

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

  • Constructor Details

    • Solution

      public Solution()

  • Method Details

    • longestObstacleCourseAtEachPosition

      public int[] longestObstacleCourseAtEachPosition(int[] obstacles)