feat: azl397985856#42 python3 Code added (azl397985856#267)

* Update 42.trapping-rain-water.md

Add python code

* Update 42.trapping-rain-water.md

Co-authored-by: lucifer <azl397985856@gmail.com>

Author: jojoxiaojing

problems/42.trapping-rain-water.md

@@ -52,6 +52,10 @@ for(let i = 0; i < height.length; i++) {
 
 ## 代码
 
+代码支持 JavaScript，Python3:
+
+JavaScript Code:
+
 ```js
 
 /*
@@ -88,3 +92,30 @@ var trap = function(height) {
 };
 
 ```
+
+Python Code:
+
+```python
+
+class Solution:
+    def trap(self, height: List[int]) -> int:
+        maxLeft, maxRight, volum = 0, 0, 0
+        maxLeftStack, maxRightStack = [], []
+        for h in height:
+            if h > maxLeft:
+                maxLeftStack.append(h)
+                maxLeft = h
+            else:
+                maxLeftStack.append(maxLeft)
+        for h in height[::-1]:
+            if h > maxRight:
+                maxRightStack.append(h)
+                maxRight = h
+            else:
+                maxRightStack.append(maxRight)
+        maxRightStack = maxRightStack[::-1]
+        for i in range(1, len(height) - 1):
+            minSide = min(maxLeftStack[i], maxRightStack[i])
+            volum += minSide - height[i]
+        return volum      
+```