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A stack is a linear collection that restricts element access to a single endpoint, commonly referred to as the top. This constraint enforces a Last-In-First-Out (LIFO) ordering, meaning the most recently added item is always the first to be removed. The two fundamental operations are push (insertion at the top) and pop (removal from the top). A ...

Given a string s containing only the characters '(', ')', '{', '}', '[', and ']', determine if the string is valid. A valid string satisfies: Every opening bracket must be closed by a matcihng bracket of the same type. Brackets must close in the correct order. Each closing bracket croresponds to an opening bracket of the same type. Example 1: ...

Problem A Compute the sum \(\sum_{i=1}^{n} i = \binom{n+1}{2}\). Problem B Statement: Given a string, process it from left to right. Whenever a character B is encountered, it removes itself and the character immediately to its right (if any). Output the final remaining string. Solution: Use a stack-like approach: iterate over the input and push ...

1. The time complexity of an algorithm primarily depends on ( ). A. Problem size B. CPU clock speed C. Source code length D. Quality of the compiled binary Answer: A 2. For a sequential list containing n elements, inserting a new element while preserving the existing order requires shifting ( ) elements on average. A. n B. n/2 C. 2n D. n² Answe ...

Minimum Insertions to Balance Parentheses Validating and repairing parenthesis strings requires tracking the relationship between opening and closing symbols. The algorithm monitors the current balance of unmatched left parentheses while counting necessary insertions. As we traverse the string, left parentheses increment a balance counter, whil ...

Stacks and queue are foundational linear data structures governed by LIFO and FIFO principles, respectively. This article demonstrates how to implement both using static arrays in C, C#, and C++—with redesigned logic, renamed identifiers, and structural variations while preserving correctness and clarity. Array-Based Stack Implementation A stac ...

Questions Multiple Choice Questions The basic unit of data is ( ). A. Data Structure B. Data Element C. Data Item D. File In logical terms, data structures can be classified into ( ). A. Dynamic and Static Structures B. Compact and Non-compact Structures C. Internal and External Structures D. Linear and Non-linear Structures The condition for a ...

The essence of a container adapter lies in the principle of reuse. Instead of implementing storage structures from scratch, these adapters leverage existing containers to handle data storage while exposing only the interfaces relevant to their specific access patterns. This adapter pattern represents a fundamental design philosophy in software ...

Evaluating Reverse Polish Notation Reverse Polish Notation (RPN) eliminates the need for parentheses by placing operators after their operands. A stack-based approach efficiently processes tokens in a single pass. class Solution { public: int evalRPN(vector<string>& expr) { stack<int> eval_stack; for (const a ...

Stack-Based Index Tracking Calculating the maximum length of well-formed parenthesis substrings requires maintaining a dynamic baseline for distance measurements. A stack storing character indices provides an efficient mechanism for this. Initialize the data structure with -1 to act as a virtual boundary before the string begins. Process the in ...