Largest Odd Number in String

class Solution {
public:
    string findLargestOdd(string digits) {
        for (int idx = digits.length() - 1; idx >= 0; --idx) {
            if ((digits[idx] - '0') % 2 == 1) {
                return digits.substr(0, idx + 1);
            }
        }
        return "";
    }
};

The provided C++ code defines a class Solution with a method findLargestOdd, which extracts the largest odd-numbered string from a given string of digits. The method iterates backwards from the end of the string until it finds a digit that is an odd number. Once it finds an odd digit, the method returns the substring from the start of the digit string to the position of this odd digit. If no odd digits are found in the entire scan, it returns an empty string.

Here's a break-down of how the code accomplishes this task:

• Iterates over the string from the last character to the first using a reverse loop.
• Checks if the current digit is odd by checking (digits[idx] - '0') % 2 == 1.
• When an odd digit is found, it returns the substring from the beginning to the current digit's position inclusive.
• If no odd digit is found by the end of the loop, it returns an empty string.

This solution is efficient as it makes a single pass over the input string from the end to the beginning and stops as soon as a valid result is identified.

class Solution {
    public String findLargestOdd(String digits) {
        for (int index = digits.length() - 1; index >= 0; index--) {
            if ((digits.charAt(index) - '0') % 2 == 1) {
                return digits.substring(0, index + 1);
            }
        }
        return "";
    }
}

In the "Largest Odd Number in String" problem, the objective is to extract the largest odd-numbered string based on its decimal value from a given string of numerical digits using Java.

Follow these steps in the provided code:

1. Define a class Solution with a method findLargestOdd, which accepts a String called digits.
2. Traverse the string from the end to the beginning using a reverse loop, to quickly find the highest odd significant digit.
3. In each iteration, check if the current digit is odd by using modulo operation (digits.charAt(index) - '0') % 2 == 1.
4. If an odd digit is found, use substring to return the number from the start of the string to the found odd digit (inclusive).
5. If no odd digit exists in the entire string, return an empty string.

This approach ensures efficient identification of the largest substring that forms an odd number, leveraging the properties of strings and numerical operations efficiently.

class Solution:
    def findLargestOddNumber(self, digits: str) -> str:
        for index in range(len(digits) - 1, -1, -1):
            if int(digits[index]) % 2 == 1:
                return digits[:index + 1]
            
        return ""

The provided Python code defines a function to solve the problem of finding the largest odd-numbered substring from a given string of digits. The function findLargestOddNumber processes the string from right to left, examining each character to determine if it corresponds to an odd digit by checking the modulo operation (% 2 == 1). If an odd digit is found, the function immediately returns the substring from the start of the original string up to and including the current odd digit. If no odd digit is encountered throughout the string, an empty string is returned. This approach ensures that the function efficiently finds and returns the largest odd-numbered substring without unnecessary processing.