Merge pull request #6 from mihirs16/master

added image rotate | refactored repo

Author: shushrutsharma

.gitignore

@@ -1,2 +1,3 @@
 .vscode/
-__pycache__/
+__pycache__/
+.DS_Store

03. Data Structures/Hash Tables/Valid_Sudoku.py renamed to 14. Questions/leetcode 36 - valid sudoku.py

@@ -0,0 +1,41 @@
+# rotate image | leetcode 48 | https://leetcode.com/problems/rotate-image/
+# You are given an n x n 2D matrix representing an image, rotate the image by 90 degrees (clockwise).
+# method: actual rotation
+
+# testcase 1
+# matrix: list[list[int]] = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]
+
+# testcase 2
+matrix: list[list[int]] = [[5, 1, 9, 11], [2, 4, 8, 10],[13, 3, 6, 7],[15, 14, 12, 16]]
+
+def rotate(matrix: list[list[int]]) -> None:
+    n:      int = len(matrix)   # size (n x n)
+    left:   int = 0             # left pointer
+    right:  int = n - 1         # right pointer
+    top:    int = 0             # top pointer
+    bottom: int = 0             # bottom pointer
+    temp:   int = 0             # temp variable
+
+    # if left pointer is on 
+    # the right of the right pointer
+    # stop iterating
+    while left < right:
+
+        # for each square in layer
+        for i in range(right - left):                                
+            top:    int = left
+            bottom: int = right
+            
+            temp                        = matrix[top][left + i]     # save top-left
+            matrix[top][left + i]       = matrix[bottom - i][left]  # bottom-left to top-left
+            matrix[bottom - i][left]    = matrix[bottom][right - i] # bottom-right to bottom-left
+            matrix[bottom][right - i]   = matrix[top + i][right]    # top-right to bottom-right
+            matrix[top + i][right]      = temp                      # (saved) top-left to top-right
+
+        # next layer
+        left  = left + 1                                            
+        right = right - 1
+
+# output
+rotate(matrix)
+print(matrix)

14. Questions/leetcode 48 - rotate image (by rotation).py

@@ -0,0 +1,31 @@
+# rotate image | leetcode 48 | https://leetcode.com/problems/rotate-image/
+# You are given an n x n 2D matrix representing an image, rotate the image by 90 degrees (clockwise).
+# method: transpose + reflection
+
+# testcase 1
+# matrix: list[list[int]] = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]
+
+# testcase 2
+matrix: list[list[int]] = [[5, 1, 9, 11], [2, 4, 8, 10],[13, 3, 6, 7],[15, 14, 12, 16]]
+
+def rotate(matrix: list[list[int]]) -> None:
+    n: int = len(matrix)
+
+    # transpose of the matrix
+    def transpose(matrix: list[list[int]]) -> None:
+        for i in range(n):
+            for j in range(i + 1, n):
+                matrix[i][j], matrix[j][i] = matrix[j][i], matrix[i][j]
+    
+    # reflection of the matrix
+    def reflect(matrix: list[list[int]]) -> None:
+        for i in range(n):
+            for j in range(n // 2):
+                matrix[i][j], matrix[i][n - j - 1] = matrix[i][n - j - 1], matrix[i][j]
+
+    transpose(matrix)
+    reflect(matrix)
+
+# output
+rotate(matrix)
+print(matrix)

14. Questions/leetcode 48 - rotate image (by transpose).py

@@ -1,4 +1,5 @@
 # hashset | leetcode 705 | https://leetcode.com/problems/design-hashset/
+
 class HashSet:
 
     # constructor

03. Data Structures/Hash Tables/Hash_Set.py renamed to 14. Questions/leetcode 705 - hash set.py

@@ -72,3 +72,5 @@ All the essential resources and template code needed to understand and practice
 3. [Hash Project](/13.%20Mini-Projects/hash_project)
 4. [Recursion Miniprojects](/13.%20Mini-Projects/recursion_miniprojects)
 5. [Runtime Analyser](/13.%20Mini-Projects/runtime_analyser)
+
+### 14. ❓ [Questions](/14.%20Questions/)