作者:秋忆道格 | 来源:互联网 | 2023-05-17 14:15
Aninterestingproblemaboutiterators.Thispostsharesaverynicesolution,whichisrewrittenbelow,w
An interesting problem about iterators. This post shares a very nice solution, which is rewritten below, with minor simplifications.
// Below is the interface for Iterator, which is already defined for you.
// **DO NOT** modify the interface for Iterator.
class Iterator {
struct Data;
Data* data;
public:
Iterator(const vector<int>& nums);
Iterator(const Iterator& iter);
virtual ~Iterator();
// Returns the next element in the iteration.
int next();
// Returns true if the iteration has more elements.
bool hasNext() const;
};
class PeekingIterator : public Iterator {
public:
PeekingIterator(const vector<int>& nums) : Iterator(nums) {
// Initialize any member here.
// **DO NOT** save a copy of nums and manipulate it directly.
// You should only use the Iterator interface methods.
peeked = false;
}
// Returns the next element in the iteration without advancing the iterator.
int peek() {
if (!peeked) {
peeked = true;
peekElem = Iterator::next();
}
return peekElem;
}
// hasNext() and next() should behave the same as in the Iterator interface.
// Override them if needed.
int next() {
if(peeked) {
peeked = false;
return peekElem;
}
return Iterator::next();
}
bool hasNext() const {
return peeked || Iterator::hasNext();
}
private:
bool peeked;
int peekElem;
};
BTW, it seems that we tend to misspell peek to peak. Well, after learning what peek
wants to do, I understood why it uses such a name: peek means to look furtively, which is just like what peek
does compared to next
:-)
[LeetCode] Peeking Iterator