Update Bits

Medium Update Bits

17%

Accepted

Given two 32-bit numbers, N andM, and two bit positions, i and j. Write a method to set all bits between i and j in N equal to M(e g , M becomes a substring ofN located at i and starting at j)

Have you met this question in a real interview? 

Yes

Example

Given N=(10000000000)2, M=(10101)2, i=2, j=6

return N=(10001010100)2

Note

In the function, the numbers N and M will given in decimal, you should also return a decimal number.

Challenge

Minimum number of operations?

Clarification

You can assume that the bits j through i have enough space to fit all of M. That is, if M=10011， you can assume that there are at least 5 bits between j and i. You would not, for example, have j=3 and i=2, becauseM could not fully fit between bit 3 and bit 2.

class Solution {

    /**

     *@param n, m: Two integer

     *@param i, j: Two bit positions

     *return: An integer

     */

    public int updateBits(int n, int m, int i, int j) {

        // write your code here

        

        int mask;

        if(j < 31){

            mask = ~((1 << (j + 1)) - (1 << i));

        } else{

            mask = (1 << i) - 1;

        }

        return (m << i) + (n & mask);

    }

}