From 6715c406163ec7b16c06e0b8c679531438f0abf8 Mon Sep 17 00:00:00 2001
From: sh0723 <pshpark12345@naver.com>
Date: Sat, 18 Jul 2026 13:53:01 +0900
Subject: [PATCH] =?UTF-8?q?circular=20queue=20=EA=B5=AC=ED=98=84?=
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---
 .../array/circular_queue/circular_queue.cpp   | 346 ++++++++++++++++++
 1 file changed, 346 insertions(+)
 create mode 100644 src/data_structure_implement/array/circular_queue/circular_queue.cpp

diff --git a/src/data_structure_implement/array/circular_queue/circular_queue.cpp b/src/data_structure_implement/array/circular_queue/circular_queue.cpp
new file mode 100644
index 0000000..d34f0ef
--- /dev/null
+++ b/src/data_structure_implement/array/circular_queue/circular_queue.cpp
@@ -0,0 +1,346 @@
+#include <cassert>
+#include <iostream>
+#include <stdexcept>
+using namespace std;
+class CircularQueue {
+    public:
+        CircularQueue();
+        ~CircularQueue();
+
+        void push(int value);
+        void pop();
+
+        int& front();
+        int& back();
+
+        int size() const;
+        int capacity() const;
+        bool empty() const;
+        void clear();
+        void reserve(int newCapacity);
+
+    private:
+        int* data;
+        int front_index;
+        int rear_index;
+        int current_size;
+        int current_capacity;
+
+};
+
+CircularQueue::CircularQueue(): data(nullptr),front_index(0), rear_index(0), current_size(0), current_capacity(0) {}
+
+CircularQueue::~CircularQueue() {
+    delete[] data;
+}
+
+void CircularQueue::push(int value) {
+    if(current_size == current_capacity) {
+        reserve(current_capacity==0 ? 1 : current_capacity*2);
+    }
+
+    data[rear_index] = value;
+    rear_index = (rear_index + 1) % current_capacity;
+    current_size++;
+}
+
+void CircularQueue::pop() {
+    if (current_size == 0) return;
+
+    front_index = (front_index + 1) % current_capacity;
+    current_size--;
+}
+
+
+int& CircularQueue::front() {
+    if(current_size == 0) {
+        throw out_of_range("quque is empty");
+    }
+
+    return data[front_index];
+}
+int& CircularQueue::back() {
+    if(current_size == 0) {
+        throw out_of_range("quque is empty");
+    }
+
+    int back_index = (rear_index - 1 + current_capacity) % current_capacity;
+    return data[back_index];
+}
+
+int CircularQueue::size() const{
+    return current_size;
+}
+int CircularQueue::capacity() const{
+    return current_capacity;
+}
+bool CircularQueue::empty() const{
+    return current_size == 0;
+}
+void CircularQueue::clear(){
+    current_size = 0;
+    front_index = 0;
+    rear_index = 0;
+}
+void CircularQueue::reserve(int newCapacity){
+    if (newCapacity <= current_capacity) {
+        return;
+    }
+
+    int* newData = new int[newCapacity];
+    for (int i=0; i<current_size; i++) {
+        newData[i] = data[(front_index+i)%current_capacity];
+    }
+    delete[] data;
+    data = newData;
+    current_capacity = newCapacity;
+    front_index = 0;
+    rear_index = current_size;
+}
+
+
+int main() {
+
+    CircularQueue queue;
+
+    // 1. 초기 상태
+
+    assert(queue.empty());
+
+    assert(queue.size() == 0);
+
+    assert(queue.capacity() == 0);
+
+    // 2. 첫 push
+
+    queue.push(10);
+
+    assert(!queue.empty());
+
+    assert(queue.size() == 1);
+
+    assert(queue.capacity() == 1);
+
+    assert(queue.front() == 10);
+
+    assert(queue.back() == 10);
+
+    // 3. capacity 확장
+
+    queue.push(20);
+
+    assert(queue.size() == 2);
+
+    assert(queue.capacity() == 2);
+
+    assert(queue.front() == 10);
+
+    assert(queue.back() == 20);
+
+    queue.push(30);
+
+    assert(queue.size() == 3);
+
+    assert(queue.capacity() == 4);
+
+    assert(queue.front() == 10);
+
+    assert(queue.back() == 30);
+
+    // 현재 논리적 순서: 10, 20, 30
+
+    // 4. pop
+
+    queue.pop();
+
+    assert(queue.size() == 2);
+
+    assert(queue.front() == 20);
+
+    assert(queue.back() == 30);
+
+    // 현재 논리적 순서: 20, 30
+
+    // 5. rear_index 순환 확인
+
+    queue.push(40);
+
+    queue.push(50);
+
+    assert(queue.size() == 4);
+
+    assert(queue.capacity() == 4);
+
+    assert(queue.front() == 20);
+
+    assert(queue.back() == 50);
+
+    // 내부 배열은 순환했을 수 있음
+
+    // 논리적 순서: 20, 30, 40, 50
+
+    // 6. 다시 pop 후 push
+
+    queue.pop();
+
+    queue.pop();
+
+    assert(queue.size() == 2);
+
+    assert(queue.front() == 40);
+
+    assert(queue.back() == 50);
+
+    queue.push(60);
+
+    queue.push(70);
+
+    assert(queue.size() == 4);
+
+    assert(queue.capacity() == 4);
+
+    assert(queue.front() == 40);
+
+    assert(queue.back() == 70);
+
+    // 논리적 순서: 40, 50, 60, 70
+
+    // 7. 꽉 찬 상태에서 push하여 reserve 발생
+
+    queue.push(80);
+
+    assert(queue.size() == 5);
+
+    assert(queue.capacity() == 8);
+
+    assert(queue.front() == 40);
+
+    assert(queue.back() == 80);
+
+    // reserve 후 논리적 순서 유지 확인
+
+    assert(queue.front() == 40);
+
+    // 8. front/back 참조 반환 확인
+
+    queue.front() = 400;
+
+    queue.back() = 800;
+
+    assert(queue.front() == 400);
+
+    assert(queue.back() == 800);
+
+    // 9. reserve 직접 호출
+
+    int oldSize = queue.size();
+
+    queue.reserve(20);
+
+    assert(queue.capacity() == 20);
+
+    assert(queue.size() == oldSize);
+
+    assert(queue.front() == 400);
+
+    assert(queue.back() == 800);
+
+    // 더 작은 reserve는 무시
+
+    queue.reserve(10);
+
+    assert(queue.capacity() == 20);
+
+    assert(queue.size() == oldSize);
+
+    // 10. 전부 pop
+
+    while (!queue.empty()) {
+
+        queue.pop();
+
+    }
+
+    assert(queue.empty());
+
+    assert(queue.size() == 0);
+
+    assert(queue.capacity() == 20);
+
+    // 빈 큐 pop은 아무 일도 하지 않음
+
+    queue.pop();
+
+    assert(queue.size() == 0);
+
+    // 11. 빈 큐 front 예외
+
+    bool exceptionThrown = false;
+
+    try {
+
+        queue.front();
+
+    } catch (const out_of_range&) {
+
+        exceptionThrown = true;
+
+    }
+
+    assert(exceptionThrown);
+
+    // 12. 빈 큐 back 예외
+
+    exceptionThrown = false;
+
+    try {
+
+        queue.back();
+
+    } catch (const out_of_range&) {
+
+        exceptionThrown = true;
+
+    }
+
+    assert(exceptionThrown);
+
+    // 13. clear 후 재사용
+
+    queue.push(1);
+
+    queue.push(2);
+
+    queue.push(3);
+
+    assert(queue.size() == 3);
+
+    assert(queue.front() == 1);
+
+    assert(queue.back() == 3);
+
+    int previousCapacity = queue.capacity();
+
+    queue.clear();
+
+    assert(queue.empty());
+
+    assert(queue.size() == 0);
+
+    assert(queue.capacity() == previousCapacity);
+
+    queue.push(100);
+
+    queue.push(200);
+
+    assert(queue.size() == 2);
+
+    assert(queue.front() == 100);
+
+    assert(queue.back() == 200);
+
+    cout << "ALL TESTS PASSED\n";
+
+    return 0;
+
+}
\ No newline at end of file