Find the Array Concatenation Value

Problem Description

You are given a 0-indexed integer array nums. The concatenation of two numbers is the number formed by concatenating their numerals. The concatenation value of nums is initially equal to 0. Perform operations until nums becomes empty: If nums has a size greater than one, add the value of the concatenation of the first and the last element to the concatenation value and remove those two elements from nums. If only one element exists, add its value to the concatenation value, then remove it. Return the concatenation value of nums.

Key Insights

• The problem requires simulating the process of concatenating numbers from both ends of the array.
• The concatenation operation can be achieved by converting numbers to strings, concatenating them, and then converting back to an integer.
• We can use a two-pointer approach to efficiently access the first and last elements of the array until it's empty.

Space and Time Complexity

Time Complexity: O(n), where n is the number of elements in the array (each element is processed once). Space Complexity: O(1), since we are using a constant amount of extra space for the concatenation value.

Solution

To solve this problem, we can use a two-pointer technique:

1. Initialize a pointer at the start of the array and another at the end.
2. While the array has more than one element, concatenate the values at the pointers, add the result to the concatenation value, and move the pointers inward.
3. If one element remains, add it directly to the concatenation value.
4. Return the final concatenation value.

Code Solutions