[LeetCode 67] Add Binary

문제 바로가기

Description

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Given two binary strings a and b, return their sum as a binary string.

Example 1

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• Input: a = “11”, b = “1”
• Output: “100”

Example 2

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• Input: a = “1010”, b = “1011”
• Output: “10101”

Constraints

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• 1 <= a.length, b.length <= 10^4
• a and b consist only of '0' or '1' characters.
• Each string does not contain leading zeros except for the zero itself.

Code

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내 제출

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class Solution {
    public String addBinary(String a, String b) {
        StringBuilder sb = new StringBuilder();

        int i = a.length() - 1;
        int j = b.length() - 1;
        int carry = 0;

        while (i >= 0 || j >= 0 || carry == 1) {
            int sum = carry;
            if (i >= 0) sum += a.charAt(i--) - '0';
            if (j >= 0) sum += b.charAt(j--) - '0';

            sb.append(sum % 2);
            carry = sum / 2;
        }

        //System.out.println(sb.reverse());
        return sb.reverse().toString();
    }
}

Runtime	Memory
1 ms	42.5 MB

다른 풀이

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class Solution {
    public String addBinary(String a, String b) {
        StringBuilder result = new StringBuilder();
        
        int i = a.length() - 1;
        int j = b.length() - 1;
        int carry = 0;
        
        while (i >= 0 || j >= 0 || carry == 1) {
            int sum = carry;
            
            if (i >= 0) {
                sum += a.charAt(i) - '0';
                i--;
            }
            
            if (j >= 0) {
                sum += b.charAt(j) - '0';
                j--;
            }
            
            result.append(sum % 2);
            carry = sum / 2;
        }
        
        return result.reverse().toString();
    }
}

Reference

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• https://github.com/doocs/leetcode/blob/main/solution/0000-0099/0066.Plus%20One/Solution.java