给0054.替换数字.md 加入python解法

problems/kamacoder/0054.替换数字.md

@@ -215,6 +215,46 @@ public class Main {
 }
 ```
 
+### Python：
+```python
+class Solution(object):
+    def subsitute_numbers(self, s):
+        """
+        :type s: str
+        :rtype: str
+        """
+        
+        count = sum(1 for char in s if char.isdigit()) # 统计数字的个数
+        expand_len = len(s) + (count * 5)  # 计算扩充后字符串的大小， x->number， 每有一个数字就要增加五个长度
+        res = [''] * expand_len
+        
+        new_index = expand_len - 1 # 指向扩充后字符串末尾
+        old_index = len(s) - 1 # 指向原字符串末尾
+        
+        while old_index >= 0: # 从后往前， 遇到数字替换成“number”
+            if s[old_index].isdigit():
+                res[new_index-5:new_index+1] = "number"
+                new_index -= 6
+            else:
+                res[new_index] = s[old_index]
+                new_index -= 1
+            old_index -= 1
+        
+        return "".join(res)
+        
+if __name__ == "__main__":
+    solution = Solution()
+
+    while True:
+        try:
+            s = input()
+            result = solution.subsitute_numbers(s)
+            print(result)
+        except EOFError:
+            break
+
+```
+
 ### Go：
 ````go
 package main