Merge pull request Bhupesh-V#524 from claudioMontanari/feature/inclus…

…ive_scan

Feature/inclusive scan

algorithm/inclusive_scan.md

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+# inclusive_scan
+
+**Description :**  Inclusive Scan computes a binary associative operation (`std::plus<>()` by default) on the elements from `first` (included) to `last` (excluded) and writes the results in the range starting from `d_first`; if provided an initial value will be used. Available in C++17 and above.
+
+**Example** :
+
+```cpp
+    // Compute prefix index sum of all the values in v    
+    std::cout << "\n\nPrefix index sum of v: ";
+    std::inclusive_scan(v.begin(),
+                        v.end(),
+                        std::ostream_iterator<int>(std::cout, " "));
+
+    // Compute prefix index sum of all the values in v with an initial value of 5    
+    std::cout << "\n\nPrefix index sum of v (with initial value 5): ";
+    std::inclusive_scan(v.begin(),
+                        v.end(),
+                        std::ostream_iterator<int>(std::cout, " "),
+                        std::plus<>{},
+                        5);
+
+    // Compute prefix index sum of the first 3 values in v    
+    std::cout << "\n\nPrefix index sum for first 3 elements of v: ";
+    std::inclusive_scan(v.begin(),
+                        v.begin() + 3,
+                        std::ostream_iterator<int>(std::cout, " "));
+
+    // Compute prefix index product of all the values in v    
+    std::cout << "\n\nPrefix index product of v: ";
+    std::inclusive_scan(v.begin(),
+                        v.end(),
+                        std::ostream_iterator<int>(std::cout, " "),
+                        std::multiplies<>{},
+                        1);
+```
+**[See Sample code](../snippets/algorithm/inclusive_scan.cpp)**<br>
+**[Run Code](https://rextester.com/UVR33146)**

snippets/algorithm/inclusive_scan.cpp

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+/*
+    Author : Claudio Montanari
+    Date : 26/06/1995
+    Time : 15:30
+    Description : Computes inclusive prefix binary operation on a range (sum by default).
+*/
+
+#include <iostream>
+#include <vector>
+#include <numeric>
+#include <iterator>
+
+int main() {
+    std::vector<int> v{ 1, 2, 3, 4, 3, 10 };
+
+    std::cout << "Content of v: ";
+    for (auto i : v) {
+        std::cout << i << " ";
+    }
+
+    // Compute prefix index sum of all the values in v    
+    std::cout << "\n\nPrefix index sum of v: ";
+    std::inclusive_scan(v.begin(), 
+                        v.end(),
+                        std::ostream_iterator<int>(std::cout, " "));
+
+    // Compute prefix index sum of all the values in v with an initial value of 5    
+    std::cout << "\n\nPrefix index sum of v (with initial value 5): ";
+    std::inclusive_scan(v.begin(),
+                        v.end(),
+                        std::ostream_iterator<int>(std::cout, " "),
+                        std::plus<>{},
+                        5);
+
+    // Compute prefix index sum of the first 3 values in v    
+    std::cout << "\n\nPrefix index sum for first 3 elements of v: ";
+    std::inclusive_scan(v.begin(),
+                        v.begin() + 3,
+                        std::ostream_iterator<int>(std::cout, " "));
+
+    // Compute prefix index product of all the values in v    
+    std::cout << "\n\nPrefix index product of v: ";
+    std::inclusive_scan(v.begin(), 
+                        v.end(),
+                        std::ostream_iterator<int>(std::cout, " "),
+                        std::multiplies<>{},
+                        1);
+
+    std::cout << std::endl;
+}
+