Add Binary

题目表述
Given two binary strings, return their sum (also a binary string).

The input strings are both non-empty and contains only characters 1 or 0.

Example 1:

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

Example 2:

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

分析：其实就是给定两个字符串，字符串中的值为二进制，让我们计算两个字符串中二进制相加，并返回结果。

我的Code如下：

class Solution {
    public String addBinary(String a, String b) {
        int maxLen = a.length();
        if (b.length() > maxLen) {
            maxLen = b.length();
        }

        // 把字符串a逆序存入数组A中
        int[] arrayA = new int[a.length()];
        for (int i = a.length() - 1; i >= 0; i--) {
            arrayA[a.length() - 1 - i] = Integer.parseInt(a.charAt(i) + "");
        }
        int[] arrayB = new int[b.length()];
        for (int i = b.length() - 1; i >= 0; i--) {
            arrayB[b.length() - 1 - i] = Integer.parseInt(b.charAt(i) + "");
        }

        int[] array = new int[maxLen + 1];
        if (a.length() > b.length()) {
            for (int i = 0; i < arrayA.length; i++) {
                if (i < b.length()) {
                    // 正常加
                    array[i] = arrayA[i] + arrayB[i] + array[i];
                } else {
                    // b没了，就剩a
                    array[i] = arrayA[i] + array[i];
                }
                if (array[i] > 1) {
                    int chu = array[i] / 2;
                    int yu = array[i] % 2;
                    array[i] = yu;
                    array[i + 1] = chu;
                }
            }
        } else {
            for (int i = 0; i < arrayB.length; i++) {
                if (i < a.length()) {
                    // 正常加
                    array[i] = arrayA[i] + arrayB[i] + array[i];
                } else {
                    array[i] = arrayB[i] + array[i];
                }
                if (array[i] > 1) {
                    int chu = array[i] / 2;
                    int yu = array[i] % 2;
                    array[i] = yu;
                    array[i + 1] = chu;
                }
            }
        }

        // 倒序输出array即可
        String str = "";
        for (int i = array.length - 1; i >= 0; i--) {
            if (i == array.length - 1) {
                if (array[i] == 0) {
                    continue;
                }
            }
            str += array[i] + "";
        }

        return str;
    }
}