Merge pull request #2413 from maolupku/master

加入新解法：螺旋矩阵定义4个边界

problems/0054.螺旋矩阵.md

@@ -306,6 +306,47 @@ class Solution(object):
         return result
 ```
 
+版本二：定义四个边界
+```python
+class Solution(object):
+    def spiralOrder(self, matrix):
+        """
+        :type matrix: List[List[int]]
+        :rtype: List[int]
+            """
+        if not matrix:
+            return []
+
+        rows = len(matrix)
+        cols = len(matrix[0])
+        top, bottom, left, right = 0, rows - 1, 0, cols - 1
+        print_list = []
+
+        while top <= bottom and left <= right:
+            # 从左到右
+            for i in range(left, right + 1):
+                print_list.append(matrix[top][i])
+            top += 1
+
+            # 从上到下
+            for i in range(top, bottom + 1):
+                print_list.append(matrix[i][right])
+            right -= 1
+
+            # 从右到左
+            if top <= bottom:
+                for i in range(right, left - 1, -1):
+                    print_list.append(matrix[bottom][i])
+                bottom -= 1
+
+            # 从下到上
+            if left <= right:
+                for i in range(bottom, top - 1, -1):
+                    print_list.append(matrix[i][left])
+                left += 1
+
+        return print_list
+```
 
 
 <p align="center">

problems/0059.螺旋矩阵II.md

@@ -207,6 +207,50 @@ class Solution:
         return nums
 ```
 
+版本二：定义四个边界
+```python
+class Solution(object):
+    def generateMatrix(self, n):
+        if n <= 0:
+            return []
+        
+        # 初始化 n x n 矩阵
+        matrix = [[0]*n for _ in range(n)]
+
+        # 初始化边界和起始值
+        top, bottom, left, right = 0, n-1, 0, n-1
+        num = 1
+
+        while top <= bottom and left <= right:
+            # 从左到右填充上边界
+            for i in range(left, right + 1):
+                matrix[top][i] = num
+                num += 1
+            top += 1
+
+            # 从上到下填充右边界
+            for i in range(top, bottom + 1):
+                matrix[i][right] = num
+                num += 1
+            right -= 1
+
+            # 从右到左填充下边界
+
+            for i in range(right, left - 1, -1):
+                matrix[bottom][i] = num
+                num += 1
+            bottom -= 1
+
+            # 从下到上填充左边界
+
+            for i in range(bottom, top - 1, -1):
+                matrix[i][left] = num
+                num += 1
+            left += 1
+
+        return matrix
+```
+
 ### JavaScript:
 
 ```javascript