STL源码剖析之算法：pop_heap

template <class RandomAccessIterator>
inline void pop_heap(RandomAccessIterator first, RandomAccessIterator last) {
    __pop_heap_aux(first, last, value_type(first));
}

template <class RandomAccessIterator, class T>
inline void __pop_heap_aux(RandomAccessIterator first, RandomAccessIterator last, T*) {
    __pop_heap(first, last - 1, last - 1, T(*(last-1)), distance_type(first));
}

 

template <class RandomAccessIterator, class T, class Distance>
inline void __pop_heap(RandomAccessIterator first,
                     RandomAccessIterator last,
                     RandomAccessIterator result,
                     T value, Distance*) {
    *result = *first;
    __adjust_heap(first, Distance(0), Distance(last - first), value);
}

template <class RandomAccessIterator, class Distance, class T>
void __adjust_heap(RandomAccessIterator first, Distance holeIndex,
                   Distance len, T vaule) {
    Distance topIndex = holeIndex;
    Distance secondChild = holeIndex*2 + 2;

    while(secondChild < len) {
        if(*(first + secondChild) < *(first + secondChild - 1))
            --secondChild;

        *(first + holeIndex) = *(first + secondChild);
        holeIndex = secondChild;
        secondChild = holeIndex*2 + 2;
    }

    if(secondChild == len) {
        *(first + holeIndex) = *(first + secondChild - 1);
        holeIndex = secondChild - 1;
    }

    __push_heap(first, holeIndex, topIndex, vaule);
}

注：__push_heap的源码请见 http://zxn990.blog.51cto.com/4253193/1165513

转载于:https://blog.51cto.com/zxn990/1165524