Multiply two integers without using multiplication, division and bitwise operators, and no loops

By making use of recursion, we can multiply two integers with the given constraints.

To multiply x and y, recursively add x y times.

C++

// C++ program to Multiply two integers without  
// using multiplication, division and bitwise 
//  operators, and no loops 
#include<iostream> 
  
using namespace std; 
class GFG 
{ 
      
/* function to multiply two numbers x and y*/
public : int multiply(int x, int y) 
{ 
    /* 0 multiplied with anything gives 0 */
    if(y == 0) 
    return 0; 
  
    /* Add x one by one */
    if(y > 0 ) 
    return (x + multiply(x, y-1)); 
  
    /* the case where y is negative */
    if(y < 0 ) 
    return -multiply(x, -y); 
} 
}; 
  
// Driver code 
int main() 
{ 
    GFG g; 
    cout << endl << g.multiply(5, -11); 
    getchar(); 
    return 0; 
} 
  
// This code is contributed by SoM15242 

C

#include<stdio.h> 
/* function to multiply two numbers x and y*/
int multiply(int x, int y) 
{ 
   /* 0  multiplied with anything gives 0 */
   if(y == 0) 
     return 0; 
  
   /* Add x one by one */ 
   if(y > 0 ) 
     return (x + multiply(x, y-1)); 
   
  /* the case where y is negative */ 
   if(y < 0 ) 
     return -multiply(x, -y); 
} 
  
int main() 
{ 
  printf("\n %d", multiply(5, -11)); 
  getchar(); 
  return 0; 
} 

Java

class GFG { 
      
    /* function to multiply two numbers x and y*/
    static int multiply(int x, int y) { 
          
        /* 0 multiplied with anything gives 0 */
        if (y == 0) 
            return 0; 
      
        /* Add x one by one */
        if (y > 0) 
            return (x + multiply(x, y - 1)); 
      
        /* the case where y is negative */
        if (y < 0) 
            return -multiply(x, -y); 
              
        return -1; 
    } 
      
    // Driver code 
    public static void main(String[] args) { 
          
        System.out.print("\n" + multiply(5, -11)); 
    } 
} 
  
// This code is contributed by Anant Agarwal. 

Python3

# Function to multiply two numbers 
# x and y 
def multiply(x,y): 
  
    # 0 multiplied with anything 
    # gives 0  
    if(y == 0): 
        return 0
  
    # Add x one by one  
    if(y > 0 ): 
        return (x + multiply(x, y - 1)) 
  
    # The case where y is negative 
    if(y < 0 ): 
        return -multiply(x, -y) 
      
# Driver code 
print(multiply(5, -11)) 
  
# This code is contributed by Anant Agarwal. 

C#

// Multiply two integers without 
// using multiplication, division 
// and bitwise operators, and no 
// loops 
using System; 
  
class GFG { 
      
    // function to multiply two numbers 
    // x and y 
    static int multiply(int x, int y) { 
          
        // 0 multiplied with anything gives 0 
        if (y == 0) 
            return 0; 
      
        // Add x one by one 
        if (y > 0) 
            return (x + multiply(x, y - 1)); 
      
        // the case where y is negative 
        if (y < 0) 
            return -multiply(x, -y); 
              
        return -1; 
    } 
      
    // Driver code 
    public static void Main() { 
          
        Console.WriteLine(multiply(5, -11)); 
    } 
} 
  
// This code is contributed by vt_m. 

PHP

<?php 
// function to multiply  
// two numbers x and y 
function multiply($x, $y) 
{ 
/* 0 multiplied with  
anything gives 0 */
if($y == 0) 
    return 0; 
  
/* Add x one by one */
if($y > 0 ) 
    return ($x + multiply($x,  
                          $y - 1)); 
  
/* the case where  
y is negative */
if($y < 0 ) 
    return -multiply($x, -$y); 
} 
  
// Driver Code 
echo multiply(5, -11); 
  
// This code is contributed by mits. 
?> 

Output:

-55

Time Complexity: O(y) where y is the second argument to function multiply().

Russian Peasant (Multiply two numbers using bitwise operators)

Please write comments if you find any of the above code/algorithm incorrect, or find better ways to solve the same problem.

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My Personal Notes

C++

C

Java

Python3

C#

PHP

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