# queue

***

**1. Task Queuing**

```cpp
#include <queue>

int main() {
  std::queue<Task> tasks;
  tasks.push(Task("task1"));
  tasks.push(Task("task2"));
  while (!tasks.empty()) {
    Task task = tasks.front();
    tasks.pop();
    task.execute();
  }
  return 0;
}
```

**2. Message Buffering**

```cpp
#include <queue>

int main() {
  std::queue<Message> messages;
  addMessage(Message("message1"));
  addMessage(Message("message2"));
  while (!messages.empty()) {
    Message message = messages.front();
    messages.pop();
    processMessage(message);
  }
  return 0;
}
```

**3. Print Job Queue**

```cpp
#include <queue>

int main() {
  std::queue<PrintJob> printJobs;
  addPrintJob(PrintJob("document1.pdf"));
  addPrintJob(PrintJob("document2.pdf"));
  while (!printJobs.empty()) {
    PrintJob printJob = printJobs.front();
    printJobs.pop();
    print(printJob);
  }
  return 0;
}
```

**4. Event Loop**

```cpp
#include <queue>

int main() {
  std::queue<Event> events;
  while (running) {
    Event event = events.front();
    events.pop();
    handleEvent(event);
  }
  return 0;
}
```

**5. Breadth-First Search (BFS)**

```cpp
#include <queue>

int main() {
  std::queue<Node> nodes;
  nodes.push(root);
  while (!nodes.empty()) {
    Node node = nodes.front();
    nodes.pop();
    visit(node);
    for (Node* child : node->children) {
      nodes.push(child);
    }
  }
  return 0;
}
```

**6. Depth-First Search (DFS)**

```cpp
#include <queue>

int main() {
  std::queue<Node> nodes;
  nodes.push(root);
  while (!nodes.empty()) {
    Node node = nodes.front();
    nodes.pop();
    visit(node);
    for (Node* child : node->children) {
      nodes.push(front, child);
    }
  }
  return 0;
}
```

**7. Topological Sort**

```cpp
#include <queue>

int main() {
  std::queue<Node> nodes;
  initIndegree();
  for (Node* node : vertices) {
    if (node->indegree == 0) {
      nodes.push(node);
    }
  }
  while (!nodes.empty()) {
    Node node = nodes.front();
    nodes.pop();
    visit(node);
    for (Node* neighbor : node->neighbors) {
      neighbor->indegree--;
      if (neighbor->indegree == 0) {
        nodes.push(neighbor);
      }
    }
  }
  return 0;
}
```

**8. Dijkstra's Algorithm**

```cpp
#include <queue>

int main() {
  std::queue<Node> nodes;
  nodes.push(start);
  start->distance = 0;
  while (!nodes.empty()) {
    Node node = nodes.front();
    nodes.pop();
    visit(node);
    for (Node* neighbor : node->neighbors) {
      int newDistance = node->distance + weight(node, neighbor);
      if (newDistance < neighbor->distance) {
        neighbor->distance = newDistance;
        nodes.push(neighbor);
      }
    }
  }
  return 0;
}
```

**9. Prim's Algorithm**

```cpp
#include <queue>

int main() {
  std::queue<Edge> edges;
  for (Edge* edge : graph->edges) {
    edges.push(edge);
  }
  initMST();
  while (!edges.empty()) {
    Edge edge = edges.front();
    edges.pop();
    if (isSafe(edge)) {
      addEdge(edge);
    }
  }
  return 0;
}
```

**10. Kruskal's Algorithm**

```cpp
#include <queue>

int main() {
  std::queue<Edge> edges;
  for (Edge* edge : graph->edges) {
    edges.push(edge);
  }
  initMST();
  while (!edges.empty()) {
    Edge edge = edges.front();
    edges.pop();
    if (isSafe(edge)) {
      addEdge(edge);
    }
  }
  return 0;
}
```

**11. Huffman Coding**

```cpp
#include <queue>

int main() {
  std::queue<Node> nodes;
  for (char c : alphabet) {
    nodes.push(new Node(c, getFrequency(c)));
  }
  while (nodes.size() > 1) {
    Node left = nodes.front();
    nodes.pop();
    Node right = nodes.front();
    nodes.pop();
    Node parent = new Node(left->frequency + right->frequency);
    parent->left = left;
    parent->right = right;
    nodes.push(parent);
  }
  return 0;
}
```

**12. Radix Sort**

```cpp
#include <queue>

int main() {
  std::queue<int> digits[10];
  for (int i = 0; i < 10; i++) {
    digits[i] = new std::queue<int>();
  }
  for (int i = 0; i < numbers.size(); i++) {
    digits[numbers[i] % 10].push(numbers[i]);
  }
  int index = 0;
  for (int i = 0; i < 10; i++) {
    while (!digits[i].empty()) {
      numbers[index++] = digits[i].front();
      digits[i].pop();
    }
  }
  return 0;
}
```

**13. Counting Sort**

```cpp
#include <queue>

int main() {
  std::queue<int> counts[10];
  for (int i = 0; i < 10; i++) {
    counts[i] = new std::queue<int>();
  }
  for (int i = 0; i < numbers.size(); i++) {
    counts[numbers[i]].push(numbers[i]);
  }
  int index = 0;
  for (int i = 0; i < 10; i++) {
    while (!counts[i].empty()) {
      numbers[index++] = counts[i].front();
      counts[i].pop();
    }
  }
  return 0;
}
```

**14. Bucket Sort**

```cpp
#include <queue>

int main() {
  std::queue<int> buckets[10];
  for (int i = 0; i < 10; i++) {
    buckets[i] = new std::queue<int>();
  }
  for (int i = 0; i < numbers.size(); i++) {
    buckets[numbers[i] / 10].push(numbers[i]);
  }
  int index = 0;
  for (int i = 0; i < 10; i++) {
    while (!buckets[i].empty()) {
      numbers[index++] = buckets[i].front();
      buckets[i].pop();
    }
  }
  return 0;
}
```

**15. Heap Sort**

```cpp
#include <queue>

int main() {
  std::queue<int> heap;
  for (int i = 0; i < numbers.size(); i++) {
    heap.push(numbers[i]);
  }
  while (!heap.empty()) {
    numbers[heap.size() - 1] = heap.front();
    heap.pop();
    heapify(heap, heap.size() - 1);
  }
  return 0;
}
```

**16. Quick Sort**

```cpp
#include <queue>

int main() {
  std::queue<int> left;
  std::queue<int> right;
  int pivot = numbers[0];
  for (int i = 1; i < numbers.size(); i++) {
    if (numbers[i] < pivot) {
      left.push(numbers[i]);
    } else {
      right.push(numbers[i]);
    }
  }
  while (!left.empty()) {
    numbers[left.size() - 1] = left.front();
    left.pop();
  }
  numbers[left.size()] = pivot;
  while (!right.empty()) {
    numbers[left.size() + right.size() + 1] = right.front();
    right.pop();
  }
  return 0;
}
```

**17. Merge Sort**

```cpp
#include <queue>

int main() {
  std::queue<int> left;
  std::queue<int> right;
  while (!numbers.empty()) {
    int mid = numbers.size() / 2;
    for (int i = 0; i < mid; i++) {
      left.push(numbers.front());
      numbers.pop();
    }
    for (int i = 0; i < numbers.size(); i++) {
      right.push(numbers.front());
      numbers.pop();
    }
    while (!left.empty() && !right.empty()) {
      if (left.front() < right.front()) {
        numbers.push(left.front());
        left.pop();
      } else {
        numbers.push(right.front());
        right.pop();
      }
    }
    while (!left.empty()) {
      numbers.push(left.front());
      left.pop();
    }
    while (!right.empty()) {
      numbers.push(right.front());
      right.pop();
    }
  }
  return 0;
}
```

**18. Insertion Sort**

```cpp
#include <queue>

int main() {
  std::queue<int> sorted;
  while (!numbers.empty()) {
    int key = numbers.front();
    numbers.pop();
    sorted.push(key);
    while (!sorted.empty() && sorted.back() > key) {
      numbers.push(sorted.back());
      sorted.pop();
    }
    sorted.push(key);
  }
  while (!sorted.empty()) {
    numbers.push(sorted.front());
    sorted.pop();

```