LeetCode-in-Java
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 <= 104aandbconsist only of'0'or'1'characters.- Each string does not contain leading zeros except for the zero itself.
Solution
public class Solution {
public String addBinary(String a, String b) {
char[] aArray = a.toCharArray();
char[] bArray = b.toCharArray();
StringBuilder sb = new StringBuilder();
int i = aArray.length - 1;
int j = bArray.length - 1;
int carry = 0;
while (i >= 0 || j >= 0) {
int sum = (i >= 0 ? aArray[i] - '0' : 0) + (j >= 0 ? bArray[j] - '0' : 0) + carry;
sb.append(sum % 2);
carry = sum / 2;
if (i >= 0) {
i--;
}
if (j >= 0) {
j--;
}
}
if (carry != 0) {
sb.append(carry);
}
return sb.reverse().toString();
}
}