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### How to Nail your next Technical Interview

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Return sum of two given integers `a` and `b` in the string format.

## Example

``````{
"a": "10",
"b": "20"
}
``````

Output:

``````"30"
``````

10 + 20 = 30, hence the output string will be "30"

## Notes

• The input string can have trailing zeros, but the output string should not have the trailing zeros.

• We expect you to solve this problem without using any built-in library for handling large numbers.

Constraints:

• 1 <= length of both the strings <= 105
• `a` and `b` consist of only digits

## Code For Add Strings Solution: Naive

``````/*
Asymptotic complexity in terms of the total length of input strings \`n\`:
* Time: O(n).
* Auxiliary space: O(n).
* Total space: O(n).
*/

string add_two_strings(string &a, string &b) {

int i = a.size() - 1, j = b.size() - 1, carry = 0;

// Loop till both the strings or carry is not processed.
while (i >= 0 || j >= 0 || carry) {
// Store the sum of the current digits(if exists) of both the strings with carry from the previous
// stage.
int currentSum = (i >= 0 ? a[i--] - '0' : 0) + (j >= 0 ? b[j--] - '0' : 0) + carry;

carry = currentSum / 10;
}

// Remove trailing zeros.
}

}

``````

We hope that these solutions to the Add Strings Problem have helped you level up your coding skills. You can expect problems like these at top tech companies like Amazon and Google.

If you are preparing for a tech interview at FAANG or any other Tier-1 tech company, register for Interview Kickstart’s FREE webinar to understand the best way to prepare.

Interview Kickstart offers interview preparation courses taught by FAANG+ tech leads and seasoned hiring managers. Our programs include a comprehensive curriculum, unmatched teaching methods, and career coaching to help you nail your next tech interview.

We offer 18 interview preparation courses, each tailored to a specific engineering domain or role, including the most in-demand and highest-paying domains and roles, such as:

### Try yourself in the Editor

Note: Input and Output will already be taken care of.

Return sum of two given integers `a` and `b` in the string format.

## Example

``````{
"a": "10",
"b": "20"
}
``````

Output:

``````"30"
``````

10 + 20 = 30, hence the output string will be "30"

## Notes

• The input string can have trailing zeros, but the output string should not have the trailing zeros.

• We expect you to solve this problem without using any built-in library for handling large numbers.

Constraints:

• 1 <= length of both the strings <= 105
• `a` and `b` consist of only digits

## Code For Add Strings Solution: Naive

``````/*
Asymptotic complexity in terms of the total length of input strings \`n\`:
* Time: O(n).
* Auxiliary space: O(n).
* Total space: O(n).
*/

string add_two_strings(string &a, string &b) {

int i = a.size() - 1, j = b.size() - 1, carry = 0;

// Loop till both the strings or carry is not processed.
while (i >= 0 || j >= 0 || carry) {
// Store the sum of the current digits(if exists) of both the strings with carry from the previous
// stage.
int currentSum = (i >= 0 ? a[i--] - '0' : 0) + (j >= 0 ? b[j--] - '0' : 0) + carry;

carry = currentSum / 10;
}

// Remove trailing zeros.
}

}

``````

We hope that these solutions to the Add Strings Problem have helped you level up your coding skills. You can expect problems like these at top tech companies like Amazon and Google.

If you are preparing for a tech interview at FAANG or any other Tier-1 tech company, register for Interview Kickstart’s FREE webinar to understand the best way to prepare.

Interview Kickstart offers interview preparation courses taught by FAANG+ tech leads and seasoned hiring managers. Our programs include a comprehensive curriculum, unmatched teaching methods, and career coaching to help you nail your next tech interview.

We offer 18 interview preparation courses, each tailored to a specific engineering domain or role, including the most in-demand and highest-paying domains and roles, such as:

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