小頂堆

// MinStack - 小頂堆 - 開始
template<typename T>
class MinHeap {
    int maxHeapSize;
    T * heap;
    int currentSize;
    void shiftDown(int start, int end) {
        T temp = heap[start];
        while(true) {
            int j = 2*start+1;
            if(j > end) break;
            if(j < end && heap[j] > heap[j+1]) j++;
            if(temp <= heap[j]) break;
            heap[start] = heap[j];
            start = j;
        }
        heap[start] = temp;
    }
    void shiftUp(int start) {
        T temp = heap[start];
        while(start > 0) {
            int i = (start-1)/2;
            if(heap[i] <= temp) break;
            heap[start] = heap[i];
            start = i;
        }
        heap[start] = temp;
    }
public:
    MinHeap(int size = 10000) {
        heap = new T[maxHeapSize = size];
        currentSize = 0;
    }
    ~MinHeap() {
        delete[] heap;
    }
    bool isEmpty() {
        return currentSize == 0;
    }
    bool isFull() {
        return currentSize == maxHeapSize;
    }
    void clear() {
        currentSize = 0;
    }
    void insert(T x) {
        heap[currentSize] = x;
        shiftUp(currentSize++);
    }
    T remove() {
        T x = heap[0];
        heap[0] = heap[--currentSize];
        shiftDown(0, currentSize-1);
        return x;
    }
};
// MinStack - 小頂堆 - 結束

template<typename T>
class priority_queue {
    std::vector<T> data;
    bool (*_comp)(T, T);
public:
    priority_queue(bool (*comp)(T, T) = NULL) {
        _comp = comp;
    }
    priority_queue(T *from, T *to, bool (*comp)(T, T) = NULL) {
        _comp = comp;
        data.assign(from, to);
        _comp ? std::make_heap(data.begin(), data.end(), *this)
              : std::make_heap(data.begin(), data.end());
    }
    bool operator() (T a, T b) {
        return _comp && _comp(a, b);
    }
    void push(T t) {
        data.push_back(t);
        _comp ? std::push_heap(data.begin(), data.end(), *this)
              : std::push_heap(data.begin(), data.end());
    }
    void pop() {
        _comp ? std::pop_heap(data.begin(), data.end(), *this)
              : std::pop_heap(data.begin(), data.end());
        data.pop_back();
    }
    void sort() {
        _comp ? std::sort_heap(data.begin(), data.end(), *this)
              : std::sort_heap(data.begin(), data.end());
    }
    T top() {
        return data.front();
    }
    int size() {
        return data.size();
    }
};