leetcode 67. ???????????????(Add Binary)

Posted 2021-02-13

?????????har   pre   turn   ??????   ??????   leetcode   ?????????   bin   empty   

??????

• ???????????????
• ?????? 1:
• ?????? 2:
• ?????????

???????????????

??????????????????????????????????????????????????????????????????????????????

?????????????????????????????????????????? 1 ??? 0???

?????? 1:

    ??????: a = "11", b = "1"
    ??????: "100"

?????? 2:

    ??????: a = "1010", b = "1011"
    ??????: "10101"

---

?????????

class Solution {
public:
    string addBinary(string a, string b) {
        string res = "";
        if(a.empty()){
            res = b;
        }else if(b.empty()){
            res = a;
        }else{
            int sz1 = a.size();
            int sz2 = b.size();
            int i = sz1 - 1;
            int j = sz2 - 1;
            int carry = 0;
            while(i >= 0 && j >= 0){
                int digit = int(a[i] - ???0???) + int(b[j] - ???0???) + carry;
                if(digit >= 2){
                    carry = 1;
                    digit -= 2;
                }else{
                     carry = 0;
                }
                res += char(digit + ???0???);
                i --;
                j --;
            }
            
            while(i >= 0){
                int digit = int(a[i] - ???0???) + carry;
                if(digit >= 2){
                    carry = 1;
                    digit -= 2;
                }else{
                     carry = 0;
                }
                res += char(digit + ???0???);
                i --;
            }
            
            while(j >= 0){
                int digit = int(b[j] - ???0???) + carry;
                if(digit >= 2){
                    carry = 1;
                    digit -= 2;
                }else{
                     carry = 0;
                }
                res += char(digit + ???0???);
                j --;
            }
            
            if(carry != 0){
                res += char(carry + ???0???);
            }
            res = string(res.rbegin(), res.rend());
        }
        return res;
    }
};