day 1

Author: sachuverma

Diff for: Leetcode Daily Challenge/July-2021/01. Gray Code.cpp

@@ -0,0 +1,55 @@
+/*
+Gray Code
+=========
+
+An n-bit gray code sequence is a sequence of 2n integers where:
+
+Every integer is in the inclusive range [0, 2n - 1],
+The first integer is 0,
+An integer appears no more than once in the sequence,
+The binary representation of every pair of adjacent integers differs by exactly one bit, and
+The binary representation of the first and last integers differs by exactly one bit.
+Given an integer n, return any valid n-bit gray code sequence.
+
+Example 1:
+Input: n = 2
+Output: [0,1,3,2]
+Explanation:
+The binary representation of [0,1,3,2] is [00,01,11,10].
+- 00 and 01 differ by one bit
+- 01 and 11 differ by one bit
+- 11 and 10 differ by one bit
+- 10 and 00 differ by one bit
+[0,2,3,1] is also a valid gray code sequence, whose binary representation is [00,10,11,01].
+- 00 and 10 differ by one bit
+- 10 and 11 differ by one bit
+- 11 and 01 differ by one bit
+- 01 and 00 differ by one bit
+
+Example 2:
+Input: n = 1
+Output: [0,1]
+
+Constraints:
+1 <= n <= 16
+*/
+
+class Solution
+{
+public:
+  vector<int> grayCode(int n)
+  {
+    if (n == 1)
+      return {0, 1};
+    auto prev = grayCode(n - 1);
+    auto ans = prev;
+
+    for (int i = prev.size() - 1; i >= 0; --i)
+    {
+      int num = prev[i] + pow(2, n - 1);
+      ans.push_back(num);
+    }
+
+    return ans;
+  }
+};

Diff for: Leetcode Daily Challenge/July-2021/README.md

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+# June 2021 LeetCoding Challenge
+
+| Day | Question Links                                                                                                             |           Solutions            |
+| :-: | :------------------------------------------------------------------------------------------------------------------------- | :----------------------------: |
+| 1.  | [Gray Code](https://leetcode.com/explore/challenge/card/july-leetcoding-challenge-2021/608/week-1-july-1st-july-7th/3799/) | [cpp](./01.%20Gray%20Code.cpp) |

Diff for: Leetcode Daily Challenge/README.md

@@ -14,3 +14,4 @@
 - [April](./April-2021)
 - [May](./May-2021)
 - [June](./June-2021)
+- [July](./July-2021)