Multiplication of two numbers with shift operator

For any given two numbers n and m, you have to find n*m without using any multiplication operator. 
Examples : 

Input: n = 25 , m = 13
Output: 325

Input: n = 50 , m = 16
Output: 800

We can solve this problem with the shift operator. The idea is based on the fact that every number can be represented in binary form. And multiplication with a number is equivalent to multiplication with powers of 2. Powers of 2 can be obtained using left shift operator.
Check for every set bit in the binary representation of m and for every set bit left shift n, count times where count if place value of the set bit of m and add that value to answer.
 

260

Time Complexity : O(log n)

Auxiliary Space: O(1)

We can use shift operator in loops.

260

Time Complexity : O(log(m))

Auxiliary Space: O(1)

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Russian Peasant (Multiply two numbers using bitwise operators)