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AddBinary.hpp
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AddBinary.hpp
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//Add Binary
//Given two binary strings, return their sum (also a binary string).
//For example,
//a = "11"
//b = "1"
//Return "100".
#include <string>
using namespace std;
class Solution {
public:
string addBinary(string a, string b) {
if (0 == a.size() && 0 == b.size())
return "";
if (0 == a.size())
return b;
if (0 == b.size())
return a;
while ('0' == a[0])
a.erase(0, 1);
while ('0' == b[0])
b.erase(0, 1);
if (0 == a.size() && 0 == b.size())
return "0";
if (0 == a.size())
return b;
if (0 == b.size())
return a;
while (a.size() < b.size())
{
a.insert(0,"0");
}
while (b.size() < a.size())
{
b.insert(0, "0");
}
bool carry = false;
std::string str_result;
for (int i = a.size() - 1; i >= 0; i--)
{
if ('1' == a[i] && '1' == b[i] && !carry)
{
str_result.insert(0,"0");
carry = true;
}
else if ('1' == a[i] && '1' == b[i] && carry)
{
str_result.insert(0, "1");
carry = true;
}
else if (('1' == a[i] && '0' == b[i]) ||
('0' == a[i] && '1' == b[i]))
{
if (carry)
str_result.insert(0, "0");
else
str_result.insert(0, "1");
}
else if ('0' == a[i] && '0' == b[i])
{
if (carry)
{
str_result.insert(0, "1");
carry = false;
}
else
str_result.insert(0, "0");
}
}
if (carry)
str_result.insert(0, "1");
while ('0' == str_result[0])
str_result.erase(0, 1);
return str_result;
}
};