Array Nesting

arraydepth-first search

Problem Statement

You are given an integer array nums of length n where nums is a permutation of the numbers in the range [0, n - 1] .

You should build a set s[k] = {nums[k], nums[nums[k]], nums[nums[nums[k]]], ... } subjected to the following rule:

The first element in s[k] starts with the selection of the element nums[k] of index = k .

The next element in s[k] should be nums[nums[k]] , and then nums[nums[nums[k]]] , and so on.

We stop adding right before a duplicate element occurs in s[k] .

Return the longest length of a set s[k] .

Examples

Example 1

Input: nums = [5,4,0,3,1,6,2]
Output: 4
nums[0] = 5, nums[1] = 4, nums[2] = 0, nums[3] = 3, nums[4] = 1, nums[5] = 6, nums[6] = 2.
One of the longest sets s[k]:
s[0] = {nums[0], nums[5], nums[6], nums[2]} = {5, 6, 2, 0}

Example 2

Input: nums = [0,1,2]
Output: 1

Constraints

1 <= nums.length <= 10 ^5

0 <= nums[i] < nums.length

All the values of nums are unique .

🤔

Medium

Difficulty

Topic Info

ModuleDSA

CategoryArray

Sub-topicDepth-First Search