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284.Peeking_Iterator.js
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284.Peeking_Iterator.js
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/**
* // This is the Iterator's API interface.
* // You should not implement it, or speculate about its implementation.
* function Iterator() {
* @ return {number}
* this.next = function() { // return the next number of the iterator
* ...
* };
*
* @return {boolean}
* this.hasNext = function() { // return true if it still has numbers
* ...
* };
* };
*/
/**
* @param {Iterator} iterator
*/
var PeekingIterator = function (iterator) {
this.iterator = iterator;
this.iteratorNext = this.iterator.next();
};
/**
* @return {number}
*/
PeekingIterator.prototype.peek = function () {
return this.iteratorNext;
};
/**
* @return {number}
*/
PeekingIterator.prototype.next = function () {
const next = this.iteratorNext;
this.iteratorNext = this.iterator.hasNext() ? this.iterator.next() : null
return next;
};
/**
* @return {boolean}
*/
PeekingIterator.prototype.hasNext = function () {
return this.iteratorNext != null;
};
/**
* Your PeekingIterator object will be instantiated and called as such:
* var obj = new PeekingIterator(arr)
* var param_1 = obj.peek()
* var param_2 = obj.next()
* var param_3 = obj.hasNext()
*/