SDE - 2

A string is defined as a "special sequence" if it can be partitioned into two non-empty contiguous substrings, s1 and s2, where both substrings satisfy a special palindromic property.

The property is as follows: a string is considered valid if, after removing at most one character from it, the resulting string can be rearranged to form a palindrome.

A string can be rearranged to form a palindrome if it has at most one character with an odd frequency. This means the original substring (before character removal) must have at most two characters with odd frequencies.

Your task is to determine if a given string S is a special sequence. If it is, return "Yes"; otherwise, return "No".

You are given an array charge of size n, where charge[i] represents the charge value of a system.

You must remove all systems one by one until only a single system remains. The goal is to perform these removals in an order that maximizes the charge of this final remaining system.

The operation is defined as follows:

1) When you select and remove a system, its immediate left and right neighbors (if they exist) merge.

2) The new merged system has a charge equal to the sum of the charges of the two neighbors that were merged.

3) Systems at the ends of the current array (the first or last) cannot cause a merge when removed, as they only have one neighbor.

Your task is to find the maximum possible charge of the final system.

You are given a generic (n-ary) tree structure representing a hierarchy. The tree has N nodes, numbered from 0 to N-1. The structure is described by a parent array, where the i-th element denotes the parent of node i. The root of the tree is indicated by a parent value of -1.

Your task is to write a program that counts the number of nodes at each depth (or level) of the tree. The root is at depth 0, its children are at depth 1, and so on.

Create the Low-Level Design of a Stack Overflow system.