[Data Structure] 스택 구현

src/data_structure_implement/array/stack/implement_stack.cpp

@@ -0,0 +1,174 @@
+#include <bits/stdc++.h>
+using namespace std;
+class IntStack {
+public:
+    IntStack();
+    ~IntStack();
+    void push(int num);
+    void pop();
+
+    int& top();
+    int size() const;
+    int capacity() const;
+
+    bool empty() const;
+    void clear();
+    void reserve(int new_capacity);
+private:
+    int *data;
+    int curr_capacity;
+    int curr_size;
+};
+
+IntStack::IntStack() : data(nullptr), curr_size(0), curr_capacity(0){}
+
+IntStack::~IntStack() {
+    delete[] data;
+}
+
+void IntStack::push(int num) {
+    if (curr_capacity == curr_size) {
+        if (curr_capacity == 0) {
+            reserve(1);
+        } else {
+            reserve(curr_capacity * 2);
+        }
+    }
+
+    data[curr_size] = num;
+    curr_size++;
+}
+
+void IntStack::pop() {
+    if (curr_size == 0) return;
+
+    curr_size--;
+}
+
+int& IntStack::top() {
+    if (curr_size == 0) {
+        throw out_of_range("stack is empty");
+    }
+
+    return data[curr_size-1];
+}
+
+int IntStack::size() const{
+    return curr_size;
+}
+
+int IntStack::capacity() const{
+    return curr_capacity;
+}
+
+bool IntStack::empty() const{
+    return curr_size == 0;
+}
+
+void IntStack::clear() {
+    curr_size = 0;
+}
+
+void IntStack::reserve(int new_capacity) {
+    if (new_capacity <= curr_capacity) return;
+
+    int *new_data = new int[new_capacity];
+
+    for (int i=0; i<curr_size; i++) {
+        new_data[i] = data[i];
+    }
+
+    delete[] data;
+    data = new_data;
+    curr_capacity = new_capacity;
+}
+int main() {
+    IntStack stack;
+
+    assert(stack.empty());
+    assert(stack.size() == 0);
+    assert(stack.capacity() == 0);
+
+    stack.push(10);
+
+    assert(!stack.empty());
+    assert(stack.size() == 1);
+    assert(stack.capacity() == 1);
+    assert(stack.top() == 10);
+
+    stack.push(20);
+
+    assert(stack.size() == 2);
+    assert(stack.capacity() == 2);
+    assert(stack.top() == 20);
+
+    stack.push(30);
+
+    assert(stack.size() == 3);
+    assert(stack.capacity() == 4);
+    assert(stack.top() == 30);
+
+    // top이 참조를 반환하는지 확인
+    stack.top() = 300;
+
+    assert(stack.top() == 300);
+    assert(stack.size() == 3);
+
+    stack.pop();
+
+    assert(stack.size() == 2);
+    assert(stack.top() == 20);
+
+    stack.pop();
+
+    assert(stack.size() == 1);
+    assert(stack.top() == 10);
+
+    // reserve가 기존 값과 size를 유지하는지 확인
+    stack.reserve(20);
+
+    assert(stack.capacity() == 20);
+    assert(stack.size() == 1);
+    assert(stack.top() == 10);
+
+    // 더 작은 reserve는 무시
+    stack.reserve(5);
+
+    assert(stack.capacity() == 20);
+    assert(stack.size() == 1);
+
+    // clear는 capacity를 유지
+    stack.clear();
+
+    assert(stack.empty());
+    assert(stack.size() == 0);
+    assert(stack.capacity() == 20);
+
+    // 빈 스택 pop은 아무 일도 하지 않음
+    stack.pop();
+
+    assert(stack.size() == 0);
+
+    // 빈 스택 top은 예외
+    bool exceptionThrown = false;
+
+    try {
+        stack.top();
+    } catch (const out_of_range&) {
+        exceptionThrown = true;
+    }
+
+    assert(exceptionThrown);
+
+    // clear 이후 재사용
+    stack.push(100);
+    stack.push(200);
+
+    assert(stack.size() == 2);
+    assert(stack.capacity() == 20);
+    assert(stack.top() == 200);
+
+    cout << "ALL TESTS PASSED\n";
+
+    return 0;
+}