LeetCode 67. Add Binary

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"

又是一道简单题磨叽了很久？？？弱啊。

class Solution {
public:
    string addBinary(string a, string b) {
        int lena=a.size(),lenb=b.size();
        int maxx=max(lena,lenb);
        char d[maxx+1];
        int k=0;
        int lend=maxx;
        int i=lena-1,j=lenb-1;
        while(i>=0&&j>=0)
        {
        	if(a[i]=='1'&&b[j]=='1'&&k==1)
            {
                d[lend]='1';
                k=1;
            }
            else if(a[i]=='0'&&b[j]=='0'&&k==1)
            {
                d[lend]='1';
                k=0;
            }
            else if(k==1)
            {
                d[lend]='0';
                k=1;
            }
            else if(a[i]==b[j])
            {
                d[lend]='0';
                if(a[i]=='0')
                    k=0;
                else
                    k=1;
            }
            else
            {
                k=0;
                d[lend]='1';
            }
            --i;
            --j;
            --lend;
		}
		if(lena>lenb)
		{
			for(int q=lena-lenb-1;q>=0;--q)
			{
				if(k==0)
				{	
					d[lend]=a[q];				
				}
				if(k==1)
				{
					if(a[q]=='0')
					{
						d[lend]='1';
						k=0;
					}
					else
					{
						d[lend]='0';
					}
				}
				--lend;
			}
		}
		else if(lena<lenb)
		{
			for(int q=lenb-lena-1;q>=0;--q)
			{
				if(k==0)
				{	
					d[lend]=b[q];				
				}
				if(k==1)
				{
					if(b[q]=='0')
					{
						d[lend]='1';
						k=0;
					}
					else
					{
						d[lend]='0';
					}
				}
				--lend;
			}
		}
		if(k==1)
			d[0]='1';
		else
			d[0]='0';
		string c(d);
        c.erase(c.begin()+maxx+1,c.end());
		if(c[0]=='0')
			c.erase(c.begin());
        return c;
    }
};

再看看别人家的代码，差距还是很大。

class Solution
{
public:
    string addBinary(string a, string b)
    {
        string s = "";
        
        int c = 0, i = a.size() - 1, j = b.size() - 1;
        while(i >= 0 || j >= 0 || c == 1)
        {
            c += i >= 0 ? a[i --] - '0' : 0;
            c += j >= 0 ? b[j --] - '0' : 0;
            s = char(c % 2 + '0') + s;
            c /= 2;
        }
        
        return s;
    }
};