Mastering the C++ STL Set Container
Core Concepts of the Set Container
The std::set container in C++ is an associative container designed to store unique elements. Its defining characteristics include automatic sorting upon insertion and strict uniqueness of values. Unlike sequence containers, data access and insertion in a set are handled via specific member functions rather tha ...
Posted on Wed, 26 Aug 2026 16:33:47 +0000 by nephish
NowCoder Weekly Contest Round 51 Solutions
Problem A: Simple Calculation
Given an integer m, output the ceiling of m/2.
#include <bits/stdc++.h>
using namespace std;
using int64 = long long;
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
int64 m;
cin >> m;
cout << (m + 1) / 2 << '\n';
return 0;
}
Problem B: Digit Sum D ...
Posted on Wed, 26 Aug 2026 16:21:38 +0000 by koray
Integrating OpenGL Rendering in Qt6 with QOpenGLWidget
1. Creating the OpenGL Window
Inherit QOpenGLWidget: Provides a rendering viewport, functionally similar to GLFW.
Inherit QOpenGLFunctions: Provides initializeOpenGLFunctions() to retrieve OpenGL function pointers from the driver, analogous to GLAD.
Member QOpenGLShaderProgram *program_;: Stores the shader script context.
GLFW provides a cro ...
Posted on Tue, 25 Aug 2026 16:38:42 +0000 by danscreations
Building a Searchable Autocomplete Box in Qt with Preview Dropdown
A search widget featuring real-time filtering and a preview dropdown can be implemented by combining a model/view architecture with custom proxy filtering. Below is a breakdown of the approach to create a control that accepts a data set, filters rows on the fly as the user types, and displays matching results in a popup list with hover highligh ...
Posted on Tue, 25 Aug 2026 16:29:15 +0000 by GravityFX
Two Sum II - Input Array Is Sorted
You are given a 1-indexed array of integers numbers that is already sorted in non-decreasing order. Find two numbers such that they add up to a specific target number. Let these two numbers be numbers[index1] and numbers[index2] where 1 <= index1 < index2 <= numbers.length.
Return the indices of the two numbers, index1 and index2, as a ...
Posted on Tue, 25 Aug 2026 16:09:18 +0000 by scoman
C++ String-Based Hexadecimal to Octal Conversion
Problem Specification
Given a set of positive hexadecimal integers, transform each into its octal equivalent. The input provides a count n (1 ≤ n ≤ 10), followed by n strings composed of digits 0-9 and uppercase letters A-F. Each string can be up to 100,000 characters long. Neither the input nor the output should contain leading zeros.
Convers ...
Posted on Mon, 24 Aug 2026 16:48:57 +0000 by Cagecrawler
Implementing Queue Using Stacks and Stack Using Queues
Implementing a Queue with Two Stacks
To simulate FIFO behavior using LIFO structures, maintain two stacks: inputStack for enqueue operations and outputStack for dequeue operations. When outputStack is empty during a pop or peek, transfer all elements from inputStack to outputStack to reverse their order.
class MyQueue {
stack<int> inp ...
Posted on Mon, 24 Aug 2026 16:27:45 +0000 by bandit8
AtCoder Beginner Contest 049 Solutions
Problem A
Determine if a given character is one of the vowels a, e, i, o, u.
A simple approach uses a hash map to store the vowels. For efficiency, characters are hashed by subtracting 'a', and a custom hash table implementation handles lookups.
template <class T, int P = 314159>
struct hashmap {
u64 id[P];
T val[P];
int rec[P ...
Posted on Mon, 24 Aug 2026 16:13:46 +0000 by noobh
Performance Analysis of Prefix vs. Postfix Increment in C++
1. Example of Prefix/Postfix Increment Operators
The following example demonstrates the implementation of prefix and postfix increment operators for a custom Integer class.
class Integer
{
public:
// ++i: first increment, then return the new value
Integer &operator++()
{
value_ += 1;
return *this;
}
// i ...
Posted on Mon, 24 Aug 2026 16:06:59 +0000 by ghadacr
Detecting Physical Monitor Count in Qt Applications
The standard Qt method counts logical desktops, which differs from physical monitor count in two primary scenarios:
Remote Desktop Sessions (Windows): When a user connects via Remote Desktop Protocol (RDP), the session may report zero active screens depending on the connection state, or the screen count might reflect the client's configuration ...
Posted on Sun, 23 Aug 2026 16:41:43 +0000 by billabong0202