From 7070f538d47753f51773d7a50a1ff566e372be42 Mon Sep 17 00:00:00 2001
From: ivan <ivan1016017@gmail.com>
Date: Thu, 14 May 2026 04:54:16 -0600
Subject: [PATCH] adding updates

---
 .../ex_16_trapping_rain_water.py              | 45 +++++++++++++++++++
 .../ex_16_trapping_rain_water.ts              | 28 ++++++++++++
 .../test_16_trapping_rain_water_round_23.py   | 17 +++++++
 3 files changed, 90 insertions(+)
 create mode 100644 src/my_project/interviews/top_150_questions_round_23/ex_16_trapping_rain_water.py
 create mode 100644 src/my_project/interviews_typescript/top_150_questions_round_23/ex_16_trapping_rain_water.ts
 create mode 100644 tests/test_150_questions_round_23/test_16_trapping_rain_water_round_23.py

diff --git a/src/my_project/interviews/top_150_questions_round_23/ex_16_trapping_rain_water.py b/src/my_project/interviews/top_150_questions_round_23/ex_16_trapping_rain_water.py
new file mode 100644
index 00000000..03530048
--- /dev/null
+++ b/src/my_project/interviews/top_150_questions_round_23/ex_16_trapping_rain_water.py
@@ -0,0 +1,45 @@
+from typing import List, Union, Collection, Mapping, Optional
+from abc import ABC, abstractmethod
+
+class Solution:
+    def trap(self, height: List[int]) -> int:
+        """
+        Calculate how much water can be trapped after raining.
+        
+        Key insight: Water trapped at position i = min(max_left, max_right) - height[i]
+        (if positive)
+        
+        Strategy: Two-pointer approach
+        - Use two pointers from both ends
+        - Track max height seen from left and right
+        - Move pointer with smaller max height (water level determined by shorter side)
+        - Add water trapped at current position
+        
+        Time: O(n), Space: O(1)
+        """
+        
+        if not height or len(height) < 3:
+            return 0
+        
+        left, right = 0, len(height) - 1
+        left_max, right_max = 0, 0
+        water_trapped = 0
+        
+        while left < right:
+            # Update max heights seen so far
+            left_max = max(left_max, height[left])
+            right_max = max(right_max, height[right])
+            
+            # Water level is determined by the shorter side
+            if left_max < right_max:
+                # Left side is shorter, so water trapped at left position
+                # is determined by left_max
+                water_trapped += left_max - height[left]
+                left += 1
+            else:
+                # Right side is shorter or equal, so water trapped at right position
+                # is determined by right_max
+                water_trapped += right_max - height[right]
+                right -= 1
+        
+        return water_trapped
diff --git a/src/my_project/interviews_typescript/top_150_questions_round_23/ex_16_trapping_rain_water.ts b/src/my_project/interviews_typescript/top_150_questions_round_23/ex_16_trapping_rain_water.ts
new file mode 100644
index 00000000..ef73ef75
--- /dev/null
+++ b/src/my_project/interviews_typescript/top_150_questions_round_23/ex_16_trapping_rain_water.ts
@@ -0,0 +1,28 @@
+function trap(height: number[]): number {
+    let solution: number = 0
+    let l: number = 0
+    let r: number = height.length
+    let i: number 
+
+    while (l < r){
+        i = 1
+
+        if (height[l] < height[r]){
+            while (height[l] > height[l+i]){
+                solution += height[l]-height[l+i]
+                i += 1
+            }
+            l += i 
+        }
+        else{
+            while (height[r] > height[r-i]){
+                solution += height[r] - height[r-i]
+                i += 1
+            }
+            r -= i 
+        }
+    }
+
+    return solution
+
+};
\ No newline at end of file
diff --git a/tests/test_150_questions_round_23/test_16_trapping_rain_water_round_23.py b/tests/test_150_questions_round_23/test_16_trapping_rain_water_round_23.py
new file mode 100644
index 00000000..efc7c3c5
--- /dev/null
+++ b/tests/test_150_questions_round_23/test_16_trapping_rain_water_round_23.py
@@ -0,0 +1,17 @@
+import unittest
+from src.my_project.interviews.top_150_questions_round_23\
+.ex_16_trapping_rain_water import Solution
+
+class TrappingWaterTestCase(unittest.TestCase):
+
+    def test_trapping_water_first_case(self):
+        solution = Solution()
+        output = solution.trap(height = [0,1,0,2,1,0,1,3,2,1,2,1])
+        target = 6
+        self.assertEqual(output, target)
+
+    def test_trapping_water_second_case(self):
+        solution = Solution()
+        output = solution.trap(height = [4,2,0,3,2,5])
+        target = 9
+        self.assertEqual(output, target)        
\ No newline at end of file