Merge pull request matthewsamuel95#807 from rajeev1202/add-strandsort

Add strand sort algorithm

Author: matthewsamuel95

README.md

@@ -175,6 +175,7 @@ ACM-ICPC Algorithms is a collection of important algorithms and data structures
    * [Exponential Search](/Search/ExponentialSearch)
 * [Sorting Algorithms](/Sorting)
    * [BogoSort](/Sorting/BogoSort)
+   * [Strand sort](/Sorting/strandsort)
    * [Bubble Sort](/Sorting/Bubble%20Sort)
    * [Bucket Sort](/Sorting/Bucket%20Sort)
    * [Cocktail Shaker Sort](/Sorting/Cocktail%20Shaker%20Sort)

Sorting/strandsort/C++/strand_sort.cpp

@@ -0,0 +1,66 @@
+#include <bits/stdc++.h> 
+using namespace std; 
+  
+// A recursive function to implement Strand 
+// sort. 
+// ip is input list of items (unsorted). 
+// op is output list of items (sorted) 
+void strandSort(list<int> &ip, list<int> &op) 
+{ 
+    // Base case : input is empty 
+    if (ip.empty()) 
+        return; 
+  
+    // Create a sorted sublist with 
+    // first item of input list as 
+    // first item of the sublist 
+    list<int> sublist; 
+    sublist.push_back(ip.front()); 
+    ip.pop_front(); 
+       
+    // Traverse remaining items of ip list 
+    for (auto it = ip.begin(); it != ip.end(); ) { 
+  
+        // If current item of input list 
+        // is greater than last added item 
+        // to sublist, move current item 
+        // to sublist as sorted order is 
+        // maintained. 
+        if (*it > sublist.back()) { 
+            sublist.push_back(*it); 
+  
+            // erase() on list removes an 
+            // item and returns iterator to 
+            // next of removed item. 
+            it = ip.erase(it); 
+        } 
+  
+        // Otherwise ignore current element 
+        else
+            it++; 
+    } 
+  
+    // Merge current sublist into output 
+    op.merge(sublist); 
+  
+    // Recur for remaining items in 
+    // input and current items in op. 
+    strandSort(ip, op); 
+} 
+  
+// Driver code 
+int main(void) 
+{ 
+    list<int> ip{10, 5, 30, 40, 2, 4, 9}; 
+  
+    // To store sorted output list 
+    list<int> op; 
+  
+    // Sorting the list 
+    strandSort(ip, op); 
+  
+    // Printing the sorted list 
+    for (auto x : op) 
+        cout << x << " "; 
+    return 0; 
+} 

Sorting/strandsort/README.md

@@ -0,0 +1,6 @@
+<h1>Strand Sort</h1>
+<p>A sort algorithm that works well if many items are in order. First, begin a sublist by moving the first item from the original list to the sublist. For each subsequent item in the original list, if it is greater than the last item of the sublist, remove it from the original list and append it to the sublist. Merge the sublist into a final, sorted list. Repeatedly extract and merge sublists until all items are sorted. Handle two or fewer items as special cases. This is a way of sorting numbers by extracting shorter sequences of already sorted numbers from an unsorted list.  </p>
+
+
+
+<a href="https://www.geeksforgeeks.org/strand-sort/">Source: GeeksforGeeks</a>