// C++ program of above implementation
#include<bits/stdc++.h>
using namespace std;

// Standard partition process of QuickSort().
// It considers the last element as pivot and
// oves all smaller element to left of it
// and greater elements to right
int partition(int *arr, int l, int r)
{
	int x = arr[r], i = l;
	for (int j = l; j <= r - 1; j++)
	{
		if (arr[j] >= x)
		{
			swap(arr[i], arr[j]);
			i++;
		}
	}
	swap(arr[i], arr[r]);
	return i;
}

int randomPartition(int *arr, int l, int r)
{
	int n = r - l + 1;
	int pivot = (rand() % 100 + 1) % n;
	swap(arr[l + pivot], arr[r]);
	return partition(arr, l, r);
}


// This function returns k'th smallest
// element in arr[l..r] using
// QuickSort based method. ASSUMPTION:
// ALL ELEMENTS IN ARR[] ARE DISTINCT
int kthSmallest(int *arr, int l,
					int r, int k)
{

	// If k is smaller than number
	// of elements in array
	if (k > 0 && k <= r - l + 1)
	{
	
		// Partition the array around last
		// element and get position of pivot
		// element in sorted array
		int pos = randomPartition(arr, l, r);

		// If position is same as k
		if (pos - l == k - 1)
		{
			return arr[pos];
		}
		
		// If position is more, recur
		// for left subarray
		if (pos - l >= k - 1)
		{
			return kthSmallest(arr, l, pos - 1, k);
		}

		// Else recur for right subarray
		return kthSmallest(arr, pos + 1, r,
						k - pos + l - 1);
	}

	// If k is more than number of
	// elements in array
	return INT_MAX;
}

// Driver Code
int main()
{
	int arr[] = {12, 3, 5, 7, 4, 19, 26};
	int n = sizeof(arr) / sizeof(arr[0]), k = 3;
	cout << "K'th smallest element is " <<
					kthSmallest(arr, 0, n - 1, k);
}

// This code is contributed by Surbhi Tyagi.
by

C++ Online Compiler

Write, Run & Share C++ code online using OneCompiler's C++ online compiler for free. It's one of the robust, feature-rich online compilers for C++ language, running on the latest version 17. Getting started with the OneCompiler's C++ compiler is simple and pretty fast. The editor shows sample boilerplate code when you choose language as C++ and start coding!

Read inputs from stdin

OneCompiler's C++ online compiler supports stdin and users can give inputs to programs using the STDIN textbox under the I/O tab. Following is a sample program which takes name as input and print your name with hello.

#include <iostream>
#include <string>
using namespace std;

int main() 
{
    string name;
    cout << "Enter name:";
    getline (cin, name);
    cout << "Hello " << name;
    return 0;
}

About C++

C++ is a widely used middle-level programming language.

  • Supports different platforms like Windows, various Linux flavours, MacOS etc
  • C++ supports OOPS concepts like Inheritance, Polymorphism, Encapsulation and Abstraction.
  • Case-sensitive
  • C++ is a compiler based language
  • C++ supports structured programming language
  • C++ provides alot of inbuilt functions and also supports dynamic memory allocation.
  • Like C, C++ also allows you to play with memory using Pointers.

Syntax help

Loops

1. If-Else:

When ever you want to perform a set of operations based on a condition If-Else is used.

if(conditional-expression) {
   //code
}
else {
   //code
}

You can also use if-else for nested Ifs and If-Else-If ladder when multiple conditions are to be performed on a single variable.

2. Switch:

Switch is an alternative to If-Else-If ladder.

switch(conditional-expression){    
case value1:    
 // code    
 break;  // optional  
case value2:    
 // code    
 break;  // optional  
......    
    
default:     
 code to be executed when all the above cases are not matched;    
}

3. For:

For loop is used to iterate a set of statements based on a condition.

for(Initialization; Condition; Increment/decrement){  
  //code  
}

4. While:

While is also used to iterate a set of statements based on a condition. Usually while is preferred when number of iterations are not known in advance.

while (condition) {  
// code 
}

5. Do-While:

Do-while is also used to iterate a set of statements based on a condition. It is mostly used when you need to execute the statements atleast once.

do {  
 // code 
} while (condition);

Functions

Function is a sub-routine which contains set of statements. Usually functions are written when multiple calls are required to same set of statements which increases re-usuability and modularity. Function gets run only when it is called.

How to declare a Function:

return_type function_name(parameters);

How to call a Function:

function_name (parameters)

How to define a Function:

return_type function_name(parameters) {  
 // code
}