added matrix

algorithms/Python/matrix/rotate_matrix.py

@@ -0,0 +1,36 @@
+## the code below explains the way to rotate matrix/image by 90 degrees
+
+# let matrix=[[1,2,3],[4,5,6],[7,8,9]]
+
+# matrix_after_rotation=[[7,4,1],[8,5,2],[9,6,3]]
+
+## algorithm:
+# -> swap rows using two pointers and then swap the index as a[i][j],a[j][i]=a[j][i],a[i][j]
+
+def matrix_rotation_90_degree(matrix):
+    ## using two pointer 
+    l,r=0,len(matrix)-1
+
+    while l < r:
+        matrix[l],matrix[r] = matrix[r],matrix[l]   ## swapping rows using two pointers
+        l+=1
+        r-=1
+    # result
+    # # matrix=[[7,8,9],[4,5,6],[1,2,3]]
+
+    ## swapping the rows and cols of every element of matrix
+
+    for i in range(len(matrix)):
+        for j in range(i,len(matrix)):
+            ## at every iteration the row is swap with the column anc vice versa
+            matrix[i][j],matrix[j][i]=matrix[j][i],matrix[i][j]
+    
+    # result
+    # matrix=[[7,4,1],[8,5,2],[9,6,3]]
+    return matrix
+
+
+#  prints([[7,4,1],[8,5,2],[9,6,3]])
+print(matrix_rotation_90_degree([[1,2,3],[4,5,6],[7,8,9]])) 
+    
+