Merge pull request #270 from neha030/dev7

Sort stack using recursion added

Author: smv1999

Data Structures/Stacks/Sort_stack_using_recursion.cpp

@@ -0,0 +1,95 @@
+/*
+Problem Statement:
+ Given a stack, sort the given stack using recursion such that the greatest element is on the top. 
+*/
+
+#include <bits/stdc++.h>
+using namespace std;
+
+void printStack(stack<int> st)
+{
+  while (!st.empty())
+  {
+    int x = st.top();
+    st.pop();
+
+    cout << x << " ";
+  }
+
+  return;
+}
+
+void insert(stack<int> &st, int temp)
+{
+  // base condition
+  if (st.size() == 0 || st.top() < temp)
+  {
+    st.push(temp);
+    return;
+  }
+
+  int val = st.top();
+  st.pop();
+
+  insert(st, temp);
+  st.push(val);
+
+  return;
+}
+
+void sortStack(stack<int> &st)
+{
+  // base condition
+  if (st.size() == 0)
+    return;
+
+  int temp = st.top();
+  st.pop();
+
+  // recursion
+  sortStack(st);
+
+  // function to insert element in stack
+  insert(st, temp);
+
+  return;
+}
+
+int main()
+{
+  // input number of element in stack
+  int n;
+  cout<<"Enter the number of elements : ";
+  cin >> n;
+
+  stack<int> st;
+  cout<<"Enter the elements : ";
+  // input stack elements
+  for (int i = 0; i < n; i++)
+  {
+    int x;
+    cin >> x;
+
+    st.push(x);
+  }
+  cout<<"After Sorting : ";
+  // function to sort stack
+  sortStack(st);
+
+  // function to print stack element
+  printStack(st);
+
+  cout << endl;
+
+  return 0;
+}
+
+/*
+  Time Complexity: O(N*N)
+  Space complexity: O(N)
+
+  SAMPLE INPUT AND OUTPUT
+  Enter the number of elements : 10
+  Enter the elements : 9 2 5 6 0 1 7 3 4 8
+  After Sorting : 9 8 7 6 5 4 3 2 1 0         
+*/