LeetCode 67. Add Binary

67.Add Binary

题意： Given two binary strings, return their sum (also a binary string).
For example,
a = “11”
b = “1”
Return “100”.

我的思路： 这道题要理解二进制加法的机制。

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){        int sum = carry;        if(i >= 0){            sum += a.charAt(i) - '0';//表示将字符转化成数字                       }        if(j >= 0){            sum += b.charAt(j) - '0';        }        result.append(sum % 2);        carry = sum / 2;        i--;        j--;    }    if(carry != 0){        result.append(1);    }    return result.reverse().toString();//这里将上面的result字符串反转    }