Tutorial: Checking if a String is Binary

In this tutorial, we will explore how to determine if a given sequence of characters is a binary string. A binary string consists only of the characters ‘0’ and ‘1’. We will solve this problem using both C++ and Python.

Problem Statement

Given a non-empty sequence of characters str, return true if the sequence is binary, else return false.

Examples

Example 1:

Input:
str = "101"
Output:
1
Explanation:
Since the string contains only '0' and '1', the output is 1.

Example 2:

Input:
str = "75"
Output:
0
Explanation:
Since the string contains digits other than '0' and '1', the output is 0.

Requirements

• Function: isBinary(str: str) -> int
• Input: A string str
• Output: Return 1 if the string is binary, otherwise return 0.

Constraints

• 1 <= T <= 50
• 1 <= Length of str <= 10000

Approach

1. Input Handling: Ensure the function takes a string as input.
2. Character Check: Iterate through each character in the string and check if it is either ‘0’ or ‘1’.
3. Return Result: If all characters are ‘0’ or ‘1’, return 1. Otherwise, return 0.

Solution in C++

Here is the C++ implementation of the function:

#include <iostream>
#include <string>

using namespace std;

int isBinary(string str) {
    for (char c : str) {
        if (c != '0' && c != '1') {
            return 0;
        }
    }
    return 1;
}

int main() {
    int T;
    cout << "Enter number of test cases: ";
    cin >> T;
    while (T--) {
        string str;
        cout << "Enter the string: ";
        cin >> str;
        cout << isBinary(str) << endl;
    }
    return 0;
}

Solution in Python

Here is the Python implementation of the function:

pythonCopy codedef isBinary(s):
    for char in s:
        if char not in '01':
            return 0
    return 1

# Main driver code
if __name__ == "__main__":
    T = int(input("Enter number of test cases: "))
    for _ in range(T):
        s = input("Enter the string: ")
        print(isBinary(s))

Explanation

1. Input Handling: In both implementations, we start by reading the number of test cases. For each test case, we read the input string.
2. Character Check: We iterate through each character of the string. If any character is not ‘0’ or ‘1’, we return 0. If all characters are valid, we return 1.
3. Output: The output for each test case is printed on a new line.

Time and Space Complexity

• Time Complexity: O(n) where n is the length of the string. We iterate through the string once.
• Space Complexity: O(1) since we only use a few extra variables and no additional data structures proportional to the input size.

By following this tutorial, you should be able to understand the fundamental concepts behind checking if a string is binary and how to implement it in both C++ and Python.