3079. Find the Sum of Encrypted Integers 

Description

You are given an integer array nums containing positive integers. We define a function encrypt such that encrypt(x) replaces every digit in x with the largest digit in x. For example, encrypt(523) = 555 and encrypt(213) = 333.

Return the sum of encrypted elements.

Example 1:

Input: nums = [1,2,3]

Output: 6

Explanation: The encrypted elements are [1,2,3]. The sum of encrypted elements is 1 + 2 + 3 == 6.

Example 2:

Input: nums = [10,21,31]

Output: 66

Explanation: The encrypted elements are [11,22,33]. The sum of encrypted elements is 11 + 22 + 33 == 66.

Constraints:

1 <= nums.length <= 50
1 <= nums[i] <= 1000

Solutions

Solution 1: Simulation

We directly simulate the encryption process by defining a function $encrypt(x)$, which replaces each digit in an integer $x$ with the maximum digit in $x$. The implementation of the function is as follows:

We can obtain each digit of $x$ by continuously taking the modulus and integer division of $x$ by $10$, and find the maximum digit, denoted as $mx$. During the loop, we can also use a variable $p$ to record the base number of $mx$, i.e., $p = 1, 11, 111, \cdots$. Finally, return $mx \times p$.

The time complexity is $O(n \times \log M)$, where $n$ is the length of the array, and $M$ is the maximum value in the array. The space complexity is $O(1)$.

Python3

class Solution:
    def sumOfEncryptedInt(self, nums: List[int]) -> int:
        def encrypt(x: int) -> int:
            mx = p = 0
            while x:
                x, v = divmod(x, 10)
                mx = max(mx, v)
                p = p * 10 + 1
            return mx * p

        return sum(encrypt(x) for x in nums)

Java

class Solution {
    public int sumOfEncryptedInt(int[] nums) {
        int ans = 0;
        for (int x : nums) {
            ans += encrypt(x);
        }
        return ans;
    }

    private int encrypt(int x) {
        int mx = 0, p = 0;
        for (; x > 0; x /= 10) {
            mx = Math.max(mx, x % 10);
            p = p * 10 + 1;
        }
        return mx * p;
    }
}

C++

class Solution {
public:
    int sumOfEncryptedInt(vector<int>& nums) {
        auto encrypt = [&](int x) {
            int mx = 0, p = 0;
            for (; x; x /= 10) {
                mx = max(mx, x % 10);
                p = p * 10 + 1;
            }
            return mx * p;
        };
        int ans = 0;
        for (int x : nums) {
            ans += encrypt(x);
        }
        return ans;
    }
};

Go

func sumOfEncryptedInt(nums []int) (ans int) {
	encrypt := func(x int) int {
		mx, p := 0, 0
		for ; x > 0; x /= 10 {
			mx = max(mx, x%10)
			p = p*10 + 1
		}
		return mx * p
	}
	for _, x := range nums {
		ans += encrypt(x)
	}
	return
}

TypeScript

function sumOfEncryptedInt(nums: number[]): number {
    const encrypt = (x: number): number => {
        let [mx, p] = [0, 0];
        for (; x > 0; x = Math.floor(x / 10)) {
            mx = Math.max(mx, x % 10);
            p = p * 10 + 1;
        }
        return mx * p;
    };
    return nums.reduce((acc, x) => acc + encrypt(x), 0);
}