@xixi003

Leetcode-Add Binary


题目描述

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

For example,

  • a = "11"
  • b = "1"
  • Return "100".

思路

将位数补齐，类似于10进制的加法，按位进行加法运算。难点是进行进位的时候处理～

切不可转换成10进制计算，因为当数很大的时候肯定会溢出的。每次处理输入输出的时候都会遇到引号转义的问题。

好方法介绍

AC代码

#include <iostream>
#include <cstdio>
#include <string>
#include <cstdlib>
#include <cstring>


using namespace std;

string addBinary(string a, string b)
{
    	string c;
    	int flag=0;
    	int lena = a.size();
    	int lenb = b.size();
    	int len = abs(lena-lenb);
    	string append(len,'0');
    	if(lena>lenb)
    	{
    		b = append + b;
    		c.resize(lena,'0');
    	}
    	else
    	{
    		a = append + a;
    		c.resize(lenb,'0');
    	}
    	for(int j=c.size()-1;j>=0;j--)
    	{
    		int current = (a[j]-'0') ^(b[j]-'0') ^flag;
    		if((a[j]-'0') +(b[j]-'0') +flag >1)
    			flag = 1;
    		else 
    			flag = 0;
    		c[j] = current+'0';
    	}
    	if(flag == 1)
    	c = '1'+ c;
    			
    	return c;
}

int main()
{
    	string a, b;
    #ifndef add
    	freopen("in1.in","r",stdin);
    	freopen("std1.out","w",stdout);
    #endif
    	while(cin>>a>>b)
    	{
    		cout<<addBinary(a,b)<<endl;
    	}
    #ifndef add
    	fclose(stdin);
    	fclose(stdout);
    #endif
    	return 0;

}