Complement of Base 10 Integer | LeetCode 1009 | C

2023-09-12
#LeetCode #C #Bit Manipulation
LeetCode

The complement of an integer is the integer you get when you flip all the 0’s to 1’s and all the 1’s to 0’s in its binary representation.

For example, The integer 5 is “101” in binary and its complement is “010” which is the integer 2.
Given an integer n, return its complement.

Example 1:

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Input: n = 5
Output: 2
Explanation: 5 is "101" in binary, with complement "010" in binary, which is 2 in base-10.

Example 2:

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Input: n = 7
Output: 0
Explanation: 7 is "111" in binary, with complement "000" in binary, which is 0 in base-10.

Example 3:

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Input: n = 10
Output: 5
Explanation: 10 is "1010" in binary, with complement "0101" in binary, which is 5 in base-10.

Constraints:

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0 <= n < 109

Approach

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Reverse each bit and shift it back. Add the value to the result.

Algorithm

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1. Get each bit and reverse it.
2. Shift the bit back and add the value to the result.

Implementation

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int bitwiseComplement(int n){
    if(n ==0)
        return 1;
    int len = 0, result = 0, shift = 0, bit=0;
    while(n>0){
        bit = n&1;
        n>>=1;
        len++;
        if(!bit){
            result += 1 << shift;        
        }
        shift++;
    }
    return result;
}