Add Trapping Rain Water algorithm cpp

C++/Tapping_Rainwater.cpp

@@ -0,0 +1,48 @@
+#include <iostream>
+#include <vector>
+using namespace std;
+
+class Solution {
+public:
+    int trap(vector<int>& height) {
+        int n = height.size();
+        if (n < 3) return 0; // Not enough bars to trap any water
+
+        // Arrays to store the maximum height to the left and right of each bar
+        vector<int> leftMax(n), rightMax(n);
+
+        // Fill leftMax array
+        leftMax[0] = height[0];
+        for (int i = 1; i < n; i++) {
+            leftMax[i] = max(leftMax[i - 1], height[i]);
+        }
+
+        // Fill rightMax array
+        rightMax[n - 1] = height[n - 1];
+        for (int i = n - 2; i >= 0; i--) {
+            rightMax[i] = max(rightMax[i + 1], height[i]);
+        }
+
+        // Calculate the trapped water
+        int water = 0;
+        for (int i = 1; i < n - 1; i++) {
+            // The water trapped on the current bar is determined by the
+            // minimum of the maximum heights on both sides, minus the current height
+            int minHeight = min(leftMax[i], rightMax[i]);
+            if (minHeight > height[i]) {
+                water += minHeight - height[i];
+            }
+        }
+
+        return water;
+    }
+};
+
+int main() {
+    Solution solution;
+    vector<int> height = {0, 1, 0, 2, 1, 0, 1, 3, 2, 1, 2, 1};
+    int result = solution.trap(height);
+    cout << "Total water trapped: " << result << " units" << endl;
+
+    return 0;
+}