feat(54-spiral-matrix): add py3 solution

0054_spiral-matrix/python3/solution.py

@@ -0,0 +1,41 @@
+class Solution:
+    def spiralOrder(self, matrix: List[List[int]]) -> List[int]:
+        row_begin_loc, row_end_loc = 0, len(matrix) - 1
+        col_begin_loc, col_end_loc = 0, len(matrix[0]) - 1
+        result = []
+        
+        while row_begin_loc <= row_end_loc and col_begin_loc <= col_end_loc:
+            # Top Side
+            i, j = row_begin_loc, col_begin_loc
+            while j <= col_end_loc:
+                result.append(matrix[i][j])
+                j += 1
+
+            # Right Side
+            i += 1
+            j -= 1
+            while i <= row_end_loc:
+                result.append(matrix[i][j])
+                i += 1
+
+            # Bottom Side
+            i -= 1
+            j -= 1
+            while j >= col_begin_loc and i > row_begin_loc:
+                result.append(matrix[i][j])
+                j -= 1
+            
+            # Left Side
+            i -= 1
+            j += 1
+            while i > row_begin_loc and j < col_end_loc:
+                result.append(matrix[i][j])
+                i -= 1
+            
+            row_begin_loc += 1
+            row_end_loc -= 1
+            col_begin_loc += 1
+            col_end_loc -= 1
+        
+        return result
+