LeetCode 67 Add Binary (Binary addition )(*)

LeetCode 67 Add Binary (Binary addition )(*)
Translation

Given two binary strings, return their sum (also a binary string ). For example, a = "11" B = "1" returns 100 ".

Original

Given two binary strings, return their sum (also a binary string).For example,a = "11"b = "1"Return "100".

Analysis

I wrote this algorithm at the beginning. Although it has implemented the function, it does not conform to the question intention.

int ctoi(char c) {    return (int)c - 48;}int pow2(int n) {    int sum = 1;    while ((n--) > 0)        sum *= 2;    return sum;}int btoi(string s) {    int sum = 0, len = s.size();    for (int i = 0; i < len; ++i) {        sum += ctoi(s[i]) * pow2(len - i - 1);    }    return sum;}string itob(int n) {    if (n == 0) return "0";    string s = "";    while (n >= 1) {        if (n % 2 == 1)            s += "1";        else s += "0";        n /= 2;    }    string newStr = "";    for (int i = s.size() - 1; i >= 0; i--)        newStr += s[i];    return newStr;}string addBinary(string a, string b) {    return itob(btoi(a) + btoi(b));}

Then I changed the code, and I was so drunk when writing such code ......

string addBinary(string a, string b) {    if (a.size() < b.size()) swap(a, b);    int len1 = a.size(), len2 = b.size();    int comLen = len1 < len2 ? len1 : len2;    int pos = 0;    string str = "";    for (int index1 = len1 - 1, index2 = len2 - 1; index1 > len1 - comLen, index2 >= 0; index1--, index2--) {        if (pos == 0) {            if (a[index1] == '1' && b[index2] == '1') {                str += "0";                pos = 1;            }            else if (a[index1] == '0' && b[index2] == '0') {                str += "0";            }            else {                str += "1";            }        }        else if (pos == 1) {            if (a[index1] == '1' &&b[index2] == '1') {                str += "1";                pos = 1;            }            else if (a[index1] == '0' && b[index2] == '0') {                str += "1";                pos = 0;            }            else {                str += "0";                pos = 1;            }        }    }    for (int index = len1 - comLen-1; index >= 0; index--) {        if (pos == 0) {            if (a[index] == '1') {                str += "1";            }            else {                str += "0";            }        }        else if (pos == 1) {            if (a[index] == '1') {                str += "0";                pos = 1;            }            else {                str += "1";                pos = 0;            }        }    }    if (pos == 1) str += "1";    string newStr = "";    for (int i = str.size() - 1; i >= 0; i--)        newStr += str[i];    return newStr;}

I did not find any very concise code after turning around, so let's do it first ......