Careercup - Facebook面试题 - 4892713614835712

2014-05-02 09:54

题目链接

原题：

You have two numbers decomposed in binary representation, write a function that sums them and returns the result. 

Input: 100011, 100100 
Output: 1000111

题目：做二进制加法。

解法：字符串就行了，不需要额外开辟数组。string对象本身就是一个vector，也就是一个数组喽。

代码：

// http://www.careercup.com/question?id=4892713614835712
#include <iostream>
#include <string>
using namespace std;

string binaryAdd(string &a, string &b)
{
    if (a.length() > b.length()) {
        return binaryAdd(b, a);
    }
    
    string c;
    int carry;
    int na, nb;
    int bita, bitb;
    int i;

    reverse(a.begin(), a.end());
    reverse(b.begin(), b.end());
    
    na = (int)a.length();
    nb = (int)b.length();
    carry = 0;
    for (i = 0; i < nb; ++i) {
        bita = i < na ? a[i] - '0' : 0;
        bitb = b[i] - '0';
        c.push_back((bita ^ bitb ^ carry) + '0');
        carry = (bita + bitb + carry) > 1;
    }
    if (carry) {
        c.push_back('1');
    }
    reverse(c.begin(), c.end());

    return c;
}

int main()
{
    string a, b, c;
    
    while (cin >> a >> b) {
        c = binaryAdd(a, b);
        cout << c << endl;
    }
    
    return 0;
}