LeetCode 284 窥探迭代器[迭代器 构造类] HERODING的LeetCode之路

解题思路：
本质是继承 Iterator 类用来实现一个新的 Iterator 只不过多了一个peek，那么就很好解决了，next() 函数和 hasNext() 函数直接返回原来的 Iterator 的函数， peek() 函数用一个指针指向当前的位置，然后返回该指针的next即可，代码如下：

class PeekingIterator : public Iterator {
public:
	PeekingIterator(const vector& 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.
	    
	}
	
    // Returns the next element in the iteration without advancing the iterator.
	int peek() {
        auto temp = *this;
        return temp.next();
	}
	
	// hasNext() and next() should behave the same as in the Iterator interface.
	// Override them if needed.
	int next() {
	    return Iterator :: next();
	}
	
	bool hasNext() const {
	    return Iterator :: hasNext();
	}
};