堆数据结构

以下是小根堆定义，包括向堆中插入元素，删除堆中元素，建立新堆，调整堆等函数。

typedef int Elemtype;
class MinHeap{
public:
    MinHeap() :elem(0), size(0){}
    void BuildMinHeap(vector<Elemtype> v);
    void Modify(int i);
    int Delete();
    void Insert(Elemtype e);
private:
    vector<Elemtype> elem;
    int size;
};

void MinHeap::BuildMinHeap(vector<Elemtype> v)
{
    elem = v;
    size = v.size();
    int i = size / 2;
    while (i > 0){
        Modify(i);
        i--;
    }
}

void MinHeap::Modify(int i)
{
    Elemtype temp = elem[i];
    int parent, child;
    for (parent = i; parent * 2 <= size; parent = child){
        child = parent * 2;
        if (child + 1 <= size&&elem[child + 1] < elem[child])
            child++;
        if (elem[child] > temp)
            break;
        else
            elem[parent] = elem[child];
    }
    elem[parent] = temp;
}

void MinHeap::Insert(Elemtype e)
{
    elem.push_back(e);
    int i;
    i = ++size;
    for (; elem[i / 2] > e; i /= 2){
        elem[i] = elem[i / 2];
    }
    elem[i] = e;
}

int MinHeap::Delete()
{
    Elemtype temp = elem[1];
    elem[1] = elem[size--];
    elem.pop_back();
    Modify(1);
    return temp;
}