Cloudera
2020-10-05
1009. Complement of Base 10 Integer
Question:
Every non-negative integer N
has a binary representation. For example, 5
can be represented as "101"
in binary, 11
as "1011"
in binary, and so on. Note that except for N = 0
, there are no leading zeroes in any binary representation.
The complement of a binary representation is the number in binary you get when changing every 1
to a 0
and 0
to a 1
. For example, the complement of "101"
in binary is "010"
in binary.
For a given number N
in base-10, return the complement of it’s binary representation as a base-10 integer.
Example 1:
Input: 5
Output: 2
Explanation: 5 is "101" in binary, with complement "010" in binary, which is 2 in base-10.
Example 2:
Input: 7
Output: 0
Explanation: 7 is "111" in binary, with complement "000" in binary, which is 0 in base-10.
Example 3:
Input: 10
Output: 5
Explanation: 10 is "1010" in binary, with complement "0101" in binary, which is 5 in base-10.
Note:
0 <= N < 10^9
- This question is the same as 476: LeetCode Question 476
Solution:
Using XOR(^) to compare each digit with 1.
class Solution {
public int bitwiseComplement(int N) {
if (N == 0) return 1;
if (N == 1) return 0;
int orBit = 1;
int rest = N;
while (rest != 0) {
N ^= orBit;
orBit <<= 1;
rest >>= 1;
}
return N;
}
}
Using XOR(^) to compare with the largest value with current number of digits. It may have the integer overflow problem.
class Solution {
public int bitwiseComplement(int N) {
if (N == 0) return 1;
if (N == 1) return 0;
int orBit = 1;
while (orBit <= N) {
orBit <<= 1;
}
return N ^ (orBit - 1);
}
}