1017. Convert to Base -2 #

Problem #

Given a number N, return a string consisting of "0"s and "1"s that represents its value in base -2 (negative two).

The returned string must have no leading zeroes, unless the string is "0".

Example 1:

Input: 2
Output: "110"
Explantion: (-2) ^ 2 + (-2) ^ 1 = 2

Example 2:

Input: 3
Output: "111"
Explantion: (-2) ^ 2 + (-2) ^ 1 + (-2) ^ 0 = 3

Example 3:

Input: 4
Output: "100"
Explantion: (-2) ^ 2 = 4

Note:

1. 0 <= N <= 10^9

Problem Summary #

Given a number N, return a string consisting of several “0"s and “1"s, representing the value of N in base -2. The returned string must have no leading zeroes unless the string is “0”.

Note:

• 0 <= N <= 10^9

Solution Approach #

• Given a decimal number, convert it to a number in base -2
• This problem imitates the idea of converting decimal to binary; simple short division is enough.

Code #

package leetcode

import "strconv"

func baseNeg2(N int) string {
	if N == 0 {
		return "0"
	}
	res := ""
	for N != 0 {
		remainder := N % (-2)
		N = N / (-2)
		if remainder < 0 {
			remainder += 2
			N++
		}
		res = strconv.Itoa(remainder) + res
	}
	return res
}