3079. Find the Sum of Encrypted Integers

📝 Problem Details

• Title: 3079. Find the Sum of Encrypted Integers
• Link: https://leetcode.com/problems/find-the-sum-of-encrypted-integers/
• Difficulty: Easy
• Tags/Categories: Lambda Strings Math Arrays

💭What Were My Initial Thoughts?

we need to define a secondary function encrypt that can replcae every digit in an integer with the largest digit
the sumOfEncrypted Integers function needs to take all of these and return the sum

- convert the integer into a string, take its max element 
- create a new string with all characters == to the max element
- return it as an integer

- iterate through nums and sum the ecrypted integers

🤔What Did I Struggle With?

- reading the question after the mock, i realise the question was not explained correctly to me at all

💡 Explanation of Solution

same as initial thoughts

⌛ Complexity Analysis

Time Complexity:
	encrypt() : O(d) where d is the number of digits in a number
	sumOfEncryptedInt : (n * d) as we are calling the encrypt function N times

Space Complexity: O(d) where we have an additional string for each integer containing d digits

💻 Implementation of Solution

class Solution {
public:
    int sumOfEncryptedInt(vector<int>& nums) {
        // lambda function to encrypt a single number
        auto encrypt = [](int x) {
            string digits = to_string(x);
            char max_digit = *max_element(digits.begin(), digits.end()); // Find the largest digit
            string encrypted(digits.size(), max_digit); // Create the encrypted string
            return stoi(encrypted);
        };
        int encryptedSum = 0;
 
        for(int num : nums) {
            encryptedSum += encrypt(num);
        }
        return encryptedSum;
    }
};