Create Trapping Rain water.cpp

Trapping Rain water.cpp

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+#include<bits/stdc++.h> 
+using namespace std; 
+
+int findWater(int arr[], int n) 
+{ 
+    // left[i] contains height of tallest bar to the 
+    // left of i'th bar including itself 
+    int left[n]; 
+
+    // Right [i] contains height of tallest bar to 
+    // the right of ith bar including itself 
+    int right[n]; 
+
+    // Initialize result 
+    int water = 0; 
+
+    // Fill left array 
+    left[0] = arr[0]; 
+    for (int i = 1; i < n; i++) 
+       left[i] = max(left[i-1], arr[i]); 
+
+    // Fill right array 
+    right[n-1] = arr[n-1]; 
+    for (int i = n-2; i >= 0; i--) 
+       right[i] = max(right[i+1], arr[i]); 
+
+    // Calculate the accumulated water element by element 
+    // consider the amount of water on i'th bar, the 
+    // amount of water accumulated on this particular 
+    // bar will be equal to min(left[i], right[i]) - arr[i] . 
+    for (int i = 0; i < n; i++) 
+       water += min(left[i],right[i]) - arr[i]; 
+
+    return water; 
+} 
+
+// Driver program 
+int main() 
+{ 
+    int arr[] = {0, 1, 0, 2, 1, 0, 1, 3, 2, 1, 2, 1}; 
+    int n = sizeof(arr)/sizeof(arr[0]); 
+    cout << "Maximum water that can be accumulated is "
+         << findWater(arr, n); 
+    return 0; 
+}