Problem Description
You are given a 0-indexed integer array nums, where nums[i] is a digit between 0 and 9 (inclusive). The triangular sum of nums is the value of the only element present in nums after a specific process of summation and reduction.
Key Insights
- The process involves repeatedly summing adjacent elements and taking the result mod 10 until only one element remains.
- The size of the array decreases by one in each iteration.
- The final result is influenced by the cumulative effect of the summations.
Space and Time Complexity
Time Complexity: O(n^2) - Each reduction step involves O(n) operations, and there are O(n) such steps. Space Complexity: O(1) - The process can be done in place without requiring additional space proportional to the input size.
Solution
The solution involves iterating through the array and reducing its size by creating a new array that contains the sums of adjacent elements modulo 10. This is repeated until only one element remains. The data structure used here is an array, and the algorithm is a simulation of the described process.