LeetCode 67. 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".

模拟加法计算, 只不过是使用二进制格式.

class Solution {
public:
    string addBinary(string a, string b) {
        if(a.length() < b.length()) swap(a, b);
        int pa = a.length() - 1, pb = b.length() - 1, jw = 0;
        while(pb >= 0){
            a[pa] = a[pa] - '0' + b[pb] - '0' + jw + '0';
            if(a[pa] >= '2'){
                a[pa] = a[pa] % '2' + '0';
                jw = 1;
            }
            else{
                jw = 0;
            }
            pa--, pb--;
        }
        while(pa >= 0){
            a[pa] = a[pa] + jw;
            if(a[pa] >= '2'){
                a[pa] = a[pa] % '2' + '0';
                jw = 1;
            }
            else{
                jw = 0;
            }
            pa--;
        }
        if(jw){
            a.insert(a.begin(), '1');
        }
        return a;
    }
};