Given a Binary Number as string, print its 2’s complements.
2’s complement of a binary number is 1 added to the 1’s complement of the binary number. Note that 1’s complement is simply flip of given binary number.
2's complement of "0111" is "1001" 2's complement of "1100" is "0100"
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We have discussed 1’s and 2’s complements in below post.
The method discussed in above post traverses binary string twice to find 2’s complement, first finds 1’s complement, then finds 2’s complement using 1’s complement
In this post an efficient method for 2’s complement is discussed that traverses string only once. We traverse the string from last till the single 1 is not traversed and after that flip all values of string i.e. 0 to 1 and 1 to 0.
Note: Here to handle the corner case i.e. if 1 doesn’t exist in the string then just append 1 in the starting of string.
Input: str = "1000100" Output: 0111100 Explanation: Starts traversing the string from last, we got first '1' at index 4 then just flip the bits of 0 to 3 indexes to make the 2's complement. Input: str = "0000" Output: 10000 Explanation: As there is no 1 in the string so just append '1' at starting.
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