C语言 | Leetcode C语言题解之第284题窥视迭代器

题目：

题解：

bool flag;

struct PeekingIterator {
    struct Iterator *iterator;
    int nextElement;
};

struct PeekingIterator* Constructor(struct Iterator* iter) {
    struct PeekingIterator* piter = malloc(sizeof(struct PeekingIterator));
    piter->iterator = iter;
    flag = piter->iterator->hasNext();
    if(flag)
    {
        piter->nextElement = piter->iterator->next();
    }
    return piter;
}

int peek(struct PeekingIterator* obj) {
    return obj->nextElement;
}

int next(struct PeekingIterator* obj) {
    int ret = obj->nextElement;
    if(flag)
    {
        flag = obj->iterator->hasNext();
        obj->nextElement = obj->iterator->next();
    }
    return ret;
}

bool hasNext(struct PeekingIterator* obj) {
    return flag;
}