Leetcode Add Binary [Java解题报告]

public class Solution {
    public static String addBinary(String a, String b) {
        if(a.equals("")) return b;
        if(b.equals("")) return a;
        int al = a.length() - 1;    //指向a数组的末尾
        int bl = b.length() - 1;    //指向b数组的末尾
        int t = Math.max(al, bl) + 1;    
        char[] arr = new char[t+1]; //设置要创建char数组的长度
        int c = 0;
        /*char[] str1 = a.toCharArray();
        char[] str2 = b.toCharArray();*/
        for(; al>=0 && bl>=0; al--, bl--, t--) {
            int s = a.charAt(al) + b.charAt(bl) + c - ‘0‘ - ‘0‘;
            if(s==2) {
                c = 1;
                s = 0;
            } else if(s == 3) {
                c = 1;
                s = 1;
            }
            else c = 0;
            arr[t] = (char)(s+‘0‘);
        }
        while (al >= 0) {
            if(a.charAt(al) - ‘0‘ + c > 1) {
                arr[t] = 0 + ‘0‘;
                c = 1;
            } else {
                arr[t] = (char) (a.charAt(al) + c);
                c = 0;
            }
            t--;
            al--;
        }
        while (bl >= 0) {
            if(b.charAt(bl) - ‘0‘ + c > 1) {
                arr[t] = 0 + ‘0‘;
                c = 1;
            } else {
                arr[t] = (char) (b.charAt(bl) + c);
                c = 0;
            }
            t--;
            bl--;
        }
        if(c == 1) arr[0] = 1+‘0‘;
        //将数组转化为字符串输出
        return new String(arr).trim();
    }
}