package LeetCode_476
/**
* 476. Number Complement
* https://leetcode.com/problems/number-complement/description/
*
Given a positive integer num, output its complement number.The complement strategy is to flip the bits of its binary representation.
Example 1:
Input: num = 5
Output: 2
Explanation: The binary representation of 5 is 101 (no leading zero bits), and its complement is 010. So you need to output 2.
Example 2:
Input: num = 1
Output: 0
Explanation: The binary representation of 1 is 1 (no leading zero bits), and its complement is 0. So you need to output 0.
Constraints:
The given integer num is guaranteed to fit within the range of a 32-bit signed integer.
num >= 1
You could assume no leading zero bit in the integer’s binary representation.
* */
class Solution {
/*
solution 2: Decimal to binary, flip the bits then cover it to Decimal, Time:O(logn), Space:O(logn)
* */
fun bitwiseComplement(N: Int): Int {
//solution 2
val list = ArrayList<Int>()
var num = N
//decimal to binary
while (num > 0) {
list.add(num % 2)
num = num shr 1
}
//flip the binary
for (i in list.indices) {
if (list.get(i) == 1) {
list.set(i, 0)
} else {
list.set(i, 1)
}
}
var result = 0
var count = list.size - 1.0
//turn into decimal, binary to decimal by math formula: (base two) 101 = 1*2^2 + 0*2^1 + 1*2^0
while (count >= 0) {
result += list.get(count.toInt()) * Math.pow(2.0, count).toInt()
count--
}
return result
}
}
solution 1 (bit operation)
