LeetCode3.4 @ Add Binary D2F4

sunliuxun

于 2014-07-21 03:55:42 发布

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本文链接：https://blog.youkuaiyun.com/sunliuxun/article/details/38003149

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本文介绍了一种解决两个二进制字符串相加问题的方法。通过遍历输入字符串并逐位进行二进制加法运算，同时处理进位情况，最终得到结果的二进制字符串。文章提供了一个Java实现示例。

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

For example,
a = "11"
b = "1"
Return "100".

public class Solution {
    public String addBinary(String a, String b) {
        
        if(a==null || b==null)
            return null;
            
        int i=a.length()-1;
        int j=b.length()-1;
        int carry=0;
        StringBuffer sb=new StringBuffer();
        
        while(0<=i && 0<=j){
            int digit=(int)(a.charAt(i)-'0'+ b.charAt(j)-'0')+carry;//a.charAt(i)-'0' means trans str to int.
            carry=digit/2; //since its binary op, compare to /10, %10
            digit%=2;
            sb.append(digit);
            i--;
            j--;
        }//end while
        while(0<=i){  
            int digit = (int)(a.charAt(i)-'0')+carry;  
            carry=digit/2;  
            digit%=2;  
            sb.append(digit);  
            i--;  
        }  
        while(j>=0){  
            int digit=(int)(b.charAt(j)-'0')+carry;  
            carry=digit/2;  
            digit%=2;  
            sb.append(digit);  
            j--;  
        }        
        
        if(carry>0){  
            sb.append(carry);  
        }  
        
        return sb.reverse().toString();  
    }
}

http://blog.youkuaiyun.com/linhuanmars/article/details/20192227