LEARNING JOURNAL

/**
 * // This is the Iterator's API interface.
 * // You should not implement it, or speculate about its implementation
 * class Iterator {
 *      hasNext(): boolean {}
 *
 *      next(): number {}
 * }
 */

class PeekingIterator {
    private iterator:Iterator;
    private peekNum:number;

    constructor(iterator: Iterator) {
        this.iterator = iterator;
        this.peekNum = this.iterator.next();
    }

    peek(): number {
        return this.peekNum;
    }

    next(): number {
        const peekNum = this.peekNum;

        this.peekNum = this.iterator.next();

        return peekNum;
    }

    hasNext(): boolean {
        if(this.peekNum && this.peekNum >= 1) return true;

        return false;
    }   
}

/**
 * Your PeekingIterator object will be instantiated and called as such:
 * var obj = new PeekingIterator(iterator)
 * var param_1 = obj.peek()
 * var param_2 = obj.next()
 * var param_3 = obj.hasNext()
 */