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