[leetcode-341]Flatten Nested List Iterator(java)

这道题的思想是在调用hasNext的时候，将NestedInteger拆分，然后将第一个元素保存到域变量中即可。其他元素添加到链表的首部。

/** * // This is the interface that allows for creating nested lists. * // You should not implement it, or speculate about its implementation * public interface NestedInteger { * *     // @return true if this NestedInteger holds a single integer, rather than a nested list. *     public boolean isInteger(); * *     // @return the single integer that this NestedInteger holds, if it holds a single integer *     // Return null if this NestedInteger holds a nested list *     public Integer getInteger(); * *     // @return the nested list that this NestedInteger holds, if it holds a nested list *     // Return null if this NestedInteger holds a single integer *     public List<NestedInteger> getList(); * } */public class NestedIterator implements Iterator<Integer> {    List<NestedInteger> nestedList;    int data;    public NestedIterator(List<NestedInteger> nestedList) {        this.nestedList = nestedList;    }    @Override    public Integer next() {        return data;    }    @Override    public boolean hasNext() {        while(nestedList != null && nestedList.size() > 0){           NestedInteger tmpInt = nestedList.remove(0);            if(tmpInt.isInteger()){                data = tmpInt.getInteger();                return true;            }else{                nestedList.addAll(0,tmpInt.getList());            }         }        return false;    }}/** * Your NestedIterator object will be instantiated and called as such: * NestedIterator i = new NestedIterator(nestedList); * while (i.hasNext()) v[f()] = i.next(); */