day 1

Author: sachuverma

Leetcode Daily Challenge/README.md

@@ -16,3 +16,4 @@
 - [June](./June-2021)
 - [July](./July-2021)
 - [August](./August-2021)
+- [September](./September-2021)

Leetcode Daily Challenge/September-2021/01. Array Nesting.cpp

@@ -0,0 +1,56 @@
+/*
+Array Nesting
+=============
+
+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].
+
+Example 1:
+Input: nums = [5,4,0,3,1,6,2]
+Output: 4
+Explanation: 
+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 <= 105
+0 <= nums[i] < nums.length
+All the values of nums are unique.
+*/
+
+class Solution {
+public:
+    int arrayNesting(vector<int>& A) {
+        int ans = 0, n = A.size();
+        vector<int> vis (n, 0);
+        
+        for(int i = 0; i < n; ++i) {
+        
+            if(vis[i] == 0) {
+                int curr = i, count = 0;
+                
+                while(vis[curr] == 0) {
+                    vis[curr] = 1;
+                    count++;
+                    curr = A[curr];
+                }
+                
+                ans = max(ans, count);
+            }
+            
+        }
+        
+        return ans;
+    }
+};

Leetcode Daily Challenge/September-2021/README.md

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+# September 2021 LeetCoding Challenge
+
+| Day | Question Links                                                                                                                                                   |                              Solutions                               |
+| :-: | :--------------------------------------------------------------------------------------------------------------------------------------------------------------- | :------------------------------------------------------------------: |
+|     | []()  |   [cpp](./.cpp)    |
+| 1.  | [Array Nesting](https://leetcode.com/explore/featured/card/september-leetcoding-challenge-2021/636/week-1-september-1st-september-7th/3960/) | [cpp](./01.%20Array%20Nesting.cpp) |