LeetCode [67] Add Binary

 67. Add Binary

Easy

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

 

Example 1:

Input: a = "11", b = "1"
Output: "100"

Example 2:

Input: a = "1010", b = "1011"
Output: "10101"

 

Constraints:

• 1 <= a.length, b.length <= 104
• a and b consist only of '0' or '1' characters.
• Each string does not contain leading zeros except for the zero itself.

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class Solution { public String addBinary(String a, String b) { int n1 = a.length(), n2 = b.length(); int i = n1-1, j = n2-1; StringBuilder sb = new StringBuilder(); int c = 0; while(i>=0 || j>=0 || c>0){ int s = c; if(i>=0) s += a.charAt(i)-'0'; if(j>=0) s += b.charAt(j)-'0'; c = s/2; s = s%2; sb.append((char)(s+'0')); i--; j--; } return sb.reverse().toString(); } }