67 Add Binary 二进制求和
Description:
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:
Example 1:
Input: a = "11", b = "1"
Output: "100"
Example 2:
Input: a = "1010", b = "1011"
Output: "10101"
题目描述:
给定两个二进制字符串，返回他们的和（用二进制表示）。
输入为非空字符串且只包含数字 1 和 0。
示例:
示例 1:
输入: a = "11", b = "1"
输出: "100"
示例 2:
输入: a = "1010", b = "1011"
输出: "10101"
思路:
设置进位符号, 从后往前遍历
时间复杂度O(n), 空间复杂度O(n)
代码:
C++:
class Solution
{
public:
string addBinary(string a, string b)
{
string result = "";
int i = a.size() - 1, j = b.size() - 1, carry = 0;
while (i >= 0 or j >= 0)
{
int p = i >= 0 ? a[i--] - '0' : 0, q = j >= 0 ? b[j--] - '0' : 0;
int temp = p + q + carry;
result = to_string(temp % 2) + result;
carry = temp / 2;
}
return carry == 1 ? "1" + result : result;
}
};
Java:
class Solution {
public String addBinary(String a, String b) {
StringBuilder result = new StringBuilder();
int i = a.length() - 1;
int j = b.length() - 1;
int carry = 0;
while (i >= 0 || j >= 0) {
int p = i >= 0 ? a.charAt(i--) - '0' : 0;
int q = j >= 0 ? b.charAt(j--) - '0' : 0;
int temp = p + q + carry;
result.append(temp % 2);
carry = temp / 2;
}
if (carry == 1) result.append(carry);
return result.reverse().toString();
}
}
Python:
class Solution:
def addBinary(self, a: str, b: str) -> str:
return bin(int(a, 2) + int(b, 2))[2:]
