day 25

Author: sachuverma

Leetcode Daily Challenge/April-2021/25. Rotate Image.cpp

@@ -0,0 +1,53 @@
+/*
+Rotate Image
+============
+
+You are given an n x n 2D matrix representing an image, rotate the image by 90 degrees (clockwise).
+
+You have to rotate the image in-place, which means you have to modify the input 2D matrix directly. DO NOT allocate another 2D matrix and do the rotation.
+
+Example 1:
+Input: matrix = [[1,2,3],[4,5,6],[7,8,9]]
+Output: [[7,4,1],[8,5,2],[9,6,3]]
+
+Example 2:
+Input: matrix = [[5,1,9,11],[2,4,8,10],[13,3,6,7],[15,14,12,16]]
+Output: [[15,13,2,5],[14,3,4,1],[12,6,8,9],[16,7,10,11]]
+
+Example 3:
+Input: matrix = [[1]]
+Output: [[1]]
+
+Example 4:
+Input: matrix = [[1,2],[3,4]]
+Output: [[3,1],[4,2]]
+
+Constraints:
+matrix.length == n
+matrix[i].length == n
+1 <= n <= 20
+-1000 <= matrix[i][j] <= 1000
+*/
+
+class Solution
+{
+public:
+  void rotate(vector<vector<int>> &matrix)
+  {
+    for (int i = 0; i < matrix.size(); ++i)
+    {
+      for (int j = i; j < matrix.size(); ++j)
+      {
+        swap(matrix[i][j], matrix[j][i]);
+      }
+    }
+
+    for (int i = 0; i < matrix.size(); ++i)
+    {
+      for (int j = 0; j < matrix.size() / 2; ++j)
+      {
+        swap(matrix[i][j], matrix[i][matrix.size() - j - 1]);
+      }
+    }
+  }
+};

Leetcode Daily Challenge/April-2021/README.md

@@ -24,4 +24,5 @@
 | 20. | [N-ary Tree Preorder Traversal](https://leetcode.com/explore/challenge/card/april-leetcoding-challenge-2021/595/week-3-april-15th-april-21st/3714/)               |           [cpp](./20.%20N-ary%20Tree%20Preorder%20Traversal.cpp)           |
 | 21. | [Triangle](https://leetcode.com/explore/challenge/card/april-leetcoding-challenge-2021/595/week-3-april-15th-april-21st/3715/)                                    |                        [cpp](./21.%20Triangle.cpp)                         |
 | 22. | [Brick Wall](https://leetcode.com/explore/challenge/card/april-leetcoding-challenge-2021/596/week-4-april-22nd-april-28th/3717/)                                  |                      [cpp](./22.%20Brick%20Wall.cpp)                       |
-| 23. | [Count Binary Substrings](https://leetcode.com/explore/challenge/card/april-leetcoding-challenge-2021/596/week-4-april-22nd-april-28th/3718/)                                  |                      [cpp](./23.Count%20Binary%20Substrings.cpp)                       |
+| 23. | [Count Binary Substrings](https://leetcode.com/explore/challenge/card/april-leetcoding-challenge-2021/596/week-4-april-22nd-april-28th/3718/)                     |               [cpp](./23.%20Count%20Binary%20Substrings.cpp)               |
+| 25. | [Rotate Image](https://leetcode.com/explore/challenge/card/april-leetcoding-challenge-2021/596/week-4-april-22nd-april-28th/3720/)                                |                     [cpp](./25.%20Rotate%20Image.cpp)                      |