new algo

Exercise/Homework1/B 栈的实现及基本操作.cpp

@@ -0,0 +1,83 @@
+#include <iostream>
+#include <limits>
+using namespace std;
+
+template <class T>
+class Stack {
+    T* element;
+    int length;
+    int stackTop;
+
+    const T INF = std::numeric_limits<T>::max();
+
+public:
+    Stack(int l) {
+        stackTop = -1;
+        length = l;
+        element = new T[l];
+    }
+
+    ~Stack() {
+        delete[] element;
+    }
+
+    T& top() { 
+        if (stackTop == -1) throw std::invalid_argument("No Top Element.");
+        return element[stackTop];
+    }
+
+    void pop() {
+        if (stackTop == -1) throw std::invalid_argument("No Top Element.");
+        stackTop--;
+    }
+
+    void push(const T& e) {
+        if (stackTop == length - 1) {
+            T* tmp = new T[2 * length];
+            for (int i = 0; i < length; i++) {
+                tmp[i] = element[i];
+            }
+            delete[] element;
+            element = tmp;
+            length *= 2;
+        }
+        stackTop++;
+        element[stackTop] = e;
+    }
+
+    bool empty() const {
+        return stackTop == -1;
+    }
+};
+
+int main() {
+    int n;
+    cin >> n;
+    Stack<int> s(n);
+
+    for (int i = 0; i < n; i++) {
+        int p;
+        cin >> p;
+        switch (p) {
+            case 0: {
+                if (!s.empty()) {
+                    cout << s.top() << endl;
+                    s.pop();
+                } else {
+                    cout << "invalid" << endl;
+                }
+                break;
+            }
+            case 1: {
+                int val;
+                cin >> val;
+                s.push(val);
+                break;
+            }
+            default:
+                return 0;
+        }
+    }
+    return 0;
+}
+