Add Strings

class Solution {
public:
    string addStrings(string a, string b) {
        int i = a.size() - 1, j = b.size() - 1, carry = 0;
        string out;
        while (i >= 0 || j >= 0 || carry) {
            int x = (i >= 0) ? a[i--] - '0' : 0;
            int y = (j >= 0) ? b[j--] - '0' : 0;
            int s = x + y + carry;
            out.push_back('0' + s % 10);
            carry = s / 10;
        }
        reverse(out.begin(), out.end());
        return out;
    }
};

func addStrings(a string, b string) string {
    i, j, carry := len(a)-1, len(b)-1, 0
    out := []byte{}
    for i >= 0 || j >= 0 || carry > 0 {
        x, y := 0, 0
        if i >= 0 {
            x = int(a[i] - '0')
            i--
        }
        if j >= 0 {
            y = int(b[j] - '0')
            j--
        }
        s := x + y + carry
        out = append(out, byte('0'+s%10))
        carry = s / 10
    }
    for l, r := 0, len(out)-1; l < r; l, r = l+1, r-1 {
        out[l], out[r] = out[r], out[l]
    }
    return string(out)
}

class Solution:
    def addStrings(self, num1: str, num2: str) -> str:
        i, j, carry = len(num1) - 1, len(num2) - 1, 0
        out: list[str] = []
        while i >= 0 or j >= 0 or carry:
            x = ord(num1[i]) - ord('0') if i >= 0 else 0
            y = ord(num2[j]) - ord('0') if j >= 0 else 0
            s = x + y + carry
            out.append(str(s % 10))
            carry = s // 10
            i -= 1
            j -= 1
        return ''.join(reversed(out))

var addStrings = function(num1, num2) {
    let i = num1.length - 1, j = num2.length - 1, carry = 0;
    const out = [];
    while (i >= 0 || j >= 0 || carry) {
        const x = i >= 0 ? num1.charCodeAt(i--) - 48 : 0;
        const y = j >= 0 ? num2.charCodeAt(j--) - 48 : 0;
        const s = x + y + carry;
        out.push(String(s % 10));
        carry = Math.floor(s / 10);
    }
    return out.reverse().join('');
};

class Solution {
    public String addStrings(String num1, String num2) {
        int i = num1.length() - 1, j = num2.length() - 1, carry = 0;
        StringBuilder out = new StringBuilder();
        while (i >= 0 || j >= 0 || carry > 0) {
            int x = i >= 0 ? num1.charAt(i--) - '0' : 0;
            int y = j >= 0 ? num2.charAt(j--) - '0' : 0;
            int s = x + y + carry;
            out.append((char) ('0' + s % 10));
            carry = s / 10;
        }
        return out.reverse().toString();
    }
}

function addStrings(num1: string, num2: string): string {
    let i = num1.length - 1, j = num2.length - 1, carry = 0;
    const out: string[] = [];
    while (i >= 0 || j >= 0 || carry) {
        const x = i >= 0 ? num1.charCodeAt(i--) - 48 : 0;
        const y = j >= 0 ? num2.charCodeAt(j--) - 48 : 0;
        const s = x + y + carry;
        out.push(String(s % 10));
        carry = Math.floor(s / 10);
    }
    return out.reverse().join('');
}