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Leetcode 2496. Maximum Value of a String in an Array

Problem Statement

You are given an array of strings strs. Each string in the array consists of either a positive integer without leading zeros or a mix of digits and lowercase English letters.

Your task is to find the maximum value among all the strings in the array. The value of a string is defined as follows:

• If the string represents an integer, the value is equal to the integer.
• If the string contains any digits and/or lowercase English letters, the value is equal to the total length of the string.

Return the maximum value of a string in the array.

Clarifying Questions

1. Input Constraints:
   • What is the size range for the list strs?
   • What will be the maximum length of any string in the strs?
2. Edge Cases:
   • How should the function behave if an empty array is passed?
   • Will there be any strings with leading zeros that might be interpreted incorrectly?

Code

Here is the C++ solution to address the problem:

#include <iostream>
#include <vector>
#include <string>
#include <algorithm> // for std::max
#include <cctype> // for std::isdigit

using namespace std;

class Solution {
public:
    int maximumValue(vector<string>& strs) {
        int maxValue = INT_MIN;
        
        // Iterate over each string in the vector
        for (const string& s : strs) {
            bool isNumeric = true;
            
            // Check if the string is a pure number
            for (char c : s) {
                if (!isdigit(c)) {
                    isNumeric = false;
                    break;
                }
            }
            
            if (isNumeric) {
                // If it is a number, convert it to an integer and compare
                maxValue = max(maxValue, stoi(s));
            } else {
                // If it contains any letters, compare its length
                maxValue = max(maxValue, static_cast<int>(s.size()));
            }
        }
        
        return maxValue;
    }
};

int main() {
    Solution solution;
    
    vector<string> strs1 = {"123", "abc", "456", "de"};
    cout << "Maximum value: " << solution.maximumValue(strs1) << endl; // Should output 456 (integer value)
    
    vector<string> strs2 = {"a", "ab", "abc", "abcdef"};
    cout << "Maximum value: " << solution.maximumValue(strs2) << endl; // Should output 6 (length of "abcdef")
    
    return 0;
}

Strategy

1. Initialization: Start by initializing a variable maxValue to store the maximum value found so far. Set it to INT_MIN to ensure any valid number or length will be larger initially.

2. Iteration: Iterate over each string in the array:
   • Check if Numeric: Use a helper check within the loop to determine if all characters of the string are digits.
   • Calculate Value:
     • If the string contains only digits, convert it to an integer using stoi and compare it with maxValue.
     • If the string contains any letters, calculate its length and compare it with maxValue.
3. Return Result: After completing the iteration, return the maxValue.

Time Complexity

• O(n * m): Where n is the number of strings in the array, and m is the average length of the strings. The complexity arises from needing to check each character of every string to determine if it’s numeric and then either converting to integer or measuring length.

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