Merge pull request #658 from Omgupta0312/new_branch1

Rainwatertrap Problem

Program's_Contributed_By_Contributors/C++ Programs/rainwatertrap.cpp

@@ -0,0 +1,30 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+int rwt(int a[], int n)
+{
+    int res = 0;
+    int lmax[n], rmax[n];
+
+    lmax[0] = a[0];
+    for (int i = 1; i < n - 1; i++)
+        lmax[i] = max(a[i], lmax[i - 1]);
+
+    rmax[n - 1] = a[n - 1];
+    for (int i = n - 2; i >= 0; i--)
+        rmax[i] = max(a[i], rmax[i + 1]);
+
+    for (int i = 1; i < n - 1; i++)
+        res = res + min(lmax[i], rmax[i]) - a[i];
+
+    return res;
+}
+
+int main()
+{
+    int arr[] = {5, 4, 6, 0, 4, 5};
+    int n = sizeof(arr) / sizeof(arr[0]);
+    cout << rwt(arr, n) << endl;
+
+    return 0;
+}