priority_queue模拟实现

#pragma once
#include<iostream>
#include<vector>
using namespace std;
namespace m
{
    template<class T>
    struct less
    {
        bool operator()(const T& A,const T& B)
        {
            return A < B;
        }
    };

    template<class T>
    struct greater
    {
        bool operator()(const T& A, const T& B)
        {
            return A > B;
        }
    };

    template <class T, class Container = vector<T>, class Compare = less<T> >
    class priority_queue
    {
    public:
        priority_queue() = default;

        template <class InputIterator>
        priority_queue(InputIterator first, InputIterator last)
        {
            while (first != last)
            {
                this->push(*first);
                first++;
            }
        }

        bool empty() const
        {
            return c.empty();
        }
        size_t size() const
        {
            return c.size();
        }
        T top() const
        {
            return c.front();
        }

        void push(const T& x)
        {
            c.push_back(x);
            this->AdjustUP(c.size() - 1);
        }
        void pop()
        {
            if (empty())
                return;

            swap(c.front(),c.back());
            c.pop_back();
            AdjustDown(0);

        }

    private:
        void AdjustUP(int child)
        {
            int parent = (child - 1) / 2;
            while (child)
            {
                if (comp(c[parent], c[child]))
                {
                  swap(c[parent], c[child]);
                  child = parent;
                  parent = (child - 1) / 2;
                }
                else
                {
                    return;
                }
            }
        }
        void AdjustDown(int parent)
        {
            int child = 2 * parent;
            while (child < size())
            {
                if (child < size() - 1 && comp(c[child], c[child + 1]))
                {
                    child++;
                }

                if (comp(c[parent], c[child]))
                {
                    swap(c[parent], c[child]);
                    parent = child;
                    child = 2 * parent;
                }
                else
                    return;

            }
        }
        void swap(T& left, T& right)
        {
            T c = left;
            left = right;
            right = c;
        }
        Container c;
        Compare comp;
    };

};