lc281

281-ZigzagIterator

Description
Given two vectors of integers v1 and v2, implement an iterator to return their elements alternately.

Implement the ZigzagIterator class:

• ZigzagIterator(List v1, List v2) initializes the object with the two vectors v1 and v2.
• boolean hasNext() returns true if the iterator still has elements, and false otherwise.
• int next() returns the current element of the iterator and moves the iterator to the next element.

Example

Input
["MyStack", "push", "push", "top", "pop", "empty"]
[[], [1], [2], [], [], []]
Output
[null, null, null, 2, 2, false]

Explanation
MyStack myStack = new MyStack();
myStack.push(1);
myStack.push(2);
myStack.top(); // return 2
myStack.pop(); // return 2
myStack.empty(); // return False

Code

class ZigzagIterator {
private:
    queue<int> q;
public:
    
    ZigzagIterator(vector<int>& v1, vector<int>& v2) {
        int idx = 0;
        while (idx < v1.size() || idx < v2.size()) {
            if (idx < v1.size()) q.push(v1[idx]);
            if (idx < v2.size()) q.push(v2[idx]);

            idx++;
        }

    }

    int next() {
        int x = q.front();
        q.pop();
        return x;
    }

    bool hasNext() {
        return !q.empty();
    }
};

/**
 * Your ZigzagIterator object will be instantiated and called as such:
 * ZigzagIterator i(v1, v2);
 * while (i.hasNext()) cout << i.next();
 */