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Divu skaitļu reizināšana ar maiņas operatoru

Jebkuriem diviem skaitļiem n un m ir jāatrod n*m, neizmantojot reizināšanas operatoru. 
Piemēri:  

Input: n = 25  m = 13 Output: 325 Input: n = 50  m = 16 Output: 800

1. metode
Mēs varam atrisināt šo problēmu ar maiņas operatoru. Ideja ir balstīta uz faktu, ka katru skaitli var attēlot binārā formā. Un reizināšana ar skaitli ir līdzvērtīga reizināšanai ar pakāpēm 2. Pakāpes 2 var iegūt, izmantojot kreisās maiņas operatoru.
Pārbaudiet katru iestatīto bitu m binārajā attēlojumā un katru iestatīto bitu nobīdi pa kreisi n skaitīšanas reizes, kur skaitīt, ja vietas vērtība iestatītajam bitam m, un pievienojiet šo vērtību, lai atbildētu.
 

C++
// CPP program to find multiplication // of two number without use of // multiplication operator #include   using namespace std; // Function for multiplication int multiply(int n int m) {   int ans = 0 count = 0;  while (m)  {  // check for set bit and left   // shift n count times  if (m % 2 == 1)   ans += n << count;  // increment of place value (count)  count++;  m /= 2;  }  return ans; } // Driver code int main() {  int n = 20  m = 13;  cout << multiply(n m);  return 0; } 
Java
// Java program to find multiplication // of two number without use of // multiplication operator class GFG {    // Function for multiplication  static int multiply(int n int m)  {   int ans = 0 count = 0;  while (m > 0)  {  // check for set bit and left   // shift n count times  if (m % 2 == 1)   ans += n << count;    // increment of place   // value (count)  count++;  m /= 2;  }    return ans;  }    // Driver code  public static void main (String[] args)  {  int n = 20 m = 13;    System.out.print( multiply(n m) );  } } // This code is contributed by Anant Agarwal. 
Python3
# python 3 program to find multiplication # of two number without use of # multiplication operator # Function for multiplication def multiply(n m): ans = 0 count = 0 while (m): # check for set bit and left  # shift n count times if (m % 2 == 1): ans += n << count # increment of place value (count) count += 1 m = int(m/2) return ans # Driver code if __name__ == '__main__': n = 20 m = 13 print(multiply(n m)) # This code is contributed by # Ssanjit_Prasad 
C#
// C# program to find multiplication // of two number without use of // multiplication operator using System; class GFG {    // Function for multiplication  static int multiply(int n int m)  {   int ans = 0 count = 0;  while (m > 0)  {  // check for set bit and left   // shift n count times  if (m % 2 == 1)   ans += n << count;    // increment of place   // value (count)  count++;  m /= 2;  }    return ans;  }    // Driver Code  public static void Main ()  {  int n = 20 m = 13;    Console.WriteLine( multiply(n m) );  } } // This code is contributed by vt_m. 
PHP
 // PHP program to find multiplication // of two number without use of // multiplication operator // Function for multiplication function multiply( $n $m) { $ans = 0; $count = 0; while ($m) { // check for set bit and left  // shift n count times if ($m % 2 == 1) $ans += $n << $count; // increment of place value (count) $count++; $m /= 2; } return $ans; } // Driver code $n = 20 ; $m = 13; echo multiply($n $m); // This code is contributed by anuj_67. ?> 
JavaScript
<script> // JavaScript program to find multiplication  // of two number without use of  // multiplication operator  // Function for multiplication  function multiply(n m)  {   let ans = 0 count = 0;   while (m)   {   // check for set bit and left   // shift n count times   if (m % 2 == 1)   ans += n << count;   // increment of place value (count)   count++;   m = Math.floor(m / 2);   }   return ans;  }  // Driver code   let n = 20  m = 13;   document.write(multiply(n m));    // This code is contributed by Surbhi Tyagi. </script> 

Izvade
260


Laika sarežģītība: O(log n)



Palīgtelpa: O(1)

2. metode

java programmas cilpa

Mēs varam izmantot Shift operatoru cilpās.

C++
#include    using namespace std;   int multiply(int n int m){  bool isNegative = false;  if (n < 0 && m < 0) {  n = -n m = -m;  }  if (n < 0) {  n = -n isNegative = true;  }  if (m < 0) {  m = -m isNegative = true;  }   int result = 0;  while (m){  if (m & 1) {  result += n;  }  // multiply a by 2  n = n << 1;  // divide b by 2  m = m >> 1;  }  return (isNegative) ? -result : result; }   int main() {  int n = 20  m = 13;  cout << multiply(n m);  return 0; } 
Java
// Java program for the above approach import java.io.*; class GFG {    public static int multiply(int n int m){  boolean isNegative = false;  if (n < 0 && m < 0) {  n = -n;  m = -m;  }  if (n < 0) {  n = -n;  isNegative = true;  }  if (m < 0) {  m = -m;  isNegative = true;  }  int result = 0;  while (m>0){  if ((m & 1)!=0) {  result += n;  }  // multiply a by 2  n = n << 1;  // divide b by 2  m = m >> 1;  }  return (isNegative) ? -result : result; }  public static void main (String[] args) {  int n = 20  m = 13;  System.out.println(multiply(n m));  } } // This code is contributed by Pushpesh Raj. 
Python3
def multiply(n m): is_negative = False if n < 0 and m < 0: n m = -n -m if n < 0: n is_negative = -n True if m < 0: m is_negative = -m True result = 0 while m: if m & 1: result += n # multiply a by 2 n = n << 1 # divide b by 2 m = m >> 1 return -result if is_negative else result n = 20 m = 13 print(multiply(n m)) 
C#
// C# program for the above approach using System; class GFG {    public static int multiply(int n int m){  bool isNegative = false;  if (n < 0 && m < 0) {  n = -n;  m = -m;  }  if (n < 0) {  n = -n;  isNegative = true;  }  if (m < 0) {  m = -m;  isNegative = true;  }  int result = 0;  while (m>0){  if ((m & 1)!=0) {  result += n;  }  // multiply a by 2  n = n << 1;  // divide b by 2  m = m >> 1;  }  return (isNegative) ? -result : result; }  public static void Main () {  int n = 20  m = 13;  Console.WriteLine(multiply(n m));  } } // This code is contributed by Utkarsh 
JavaScript
function multiply(n m) {  let isNegative = false;  if (n < 0 && m < 0) {  n = -n m = -m;  }  if (n < 0) {  n = -n isNegative = true;  }  if (m < 0) {  m = -m isNegative = true;  }  let result = 0;  while (m) {  if (m & 1) {  result += n;  }  // multiply a by 2  n = n << 1;  // divide b by 2  m = m >> 1;  }  return (isNegative) ? -result : result; } console.log(multiply(20 13)); 

Izvade
260

Laika sarežģītība: O(log(m))

Palīgtelpa: O(1)

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