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给你一个嵌套的整数列表 nestedList 。每个元素要么是一个整数，要么是一个列表；该列表的元素也可能是整数或者是其他列表。请你实现一个迭代器将其扁平化，使之能够遍历这个列表中的所有整数。
实现扁平迭代器类 NestedIterator ：
NestedIterator(List<NestedInteger> nestedList)用嵌套列表nestedList初始化迭代器。int next()返回嵌套列表的下一个整数。boolean hasNext()如果仍然存在待迭代的整数，返回true；否则，返回false。
你的代码将会用下述伪代码检测：
initialize iterator with nestedList
res = []
while iterator.hasNext()
append iterator.next() to the end of res
return res
如果 res 与预期的扁平化列表匹配，那么你的代码将会被判为正确。
示例 1：
输入：nestedList = [[1,1],2,[1,1]]
输出：[1,1,2,1,1]
解释：通过重复调用 next 直到 hasNext 返回 false，next 返回的元素的顺序应该是: [1,1,2,1,1]。
示例 2：
输入：nestedList = [1,[4,[6]]]
输出：[1,4,6]
解释：通过重复调用 next 直到 hasNext 返回 false，next 返回的元素的顺序应该是: [1,4,6]。
提示：
1 <= nestedList.length <= 500- 嵌套列表中的整数值在范围
[-106, 106]内
根据题意要求可以将 NestedInteger 数据结构视作一个 N 叉树，当元素为一个整数时，该节点是 N 叉树的叶子节点，当元素为一个整数数组时，该节点是 N 叉树的非叶子节点，数组中的每一个元素包含子树的所有节点。故直接递归遍历 N 叉树并记录所有的叶子节点即可。
# """
# This is the interface that allows for creating nested lists.
# You should not implement it, or speculate about its implementation
# """
# class NestedInteger:
# def isInteger(self) -> bool:
# """
# @return True if this NestedInteger holds a single integer, rather than a nested list.
# """
#
# def getInteger(self) -> int:
# """
# @return the single integer that this NestedInteger holds, if it holds a single integer
# Return None if this NestedInteger holds a nested list
# """
#
# def getList(self) -> [NestedInteger]:
# """
# @return the nested list that this NestedInteger holds, if it holds a nested list
# Return None if this NestedInteger holds a single integer
# """
class NestedIterator:
def __init__(self, nestedList: [NestedInteger]):
def dfs(ls):
for x in ls:
if x.isInteger():
self.nums.append(x.getInteger())
else:
dfs(x.getList())
self.nums = []
self.i = -1
dfs(nestedList)
def next(self) -> int:
self.i += 1
return self.nums[self.i]
def hasNext(self) -> bool:
return self.i + 1 < len(self.nums)
# Your NestedIterator object will be instantiated and called as such:
# i, v = NestedIterator(nestedList), []
# while i.hasNext(): v.append(i.next())/**
* // 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 empty list if this NestedInteger holds a single integer
* public List<NestedInteger> getList();
* }
*/
public class NestedIterator implements Iterator<Integer> {
private List<Integer> nums = new ArrayList<>();
private int i = -1;
public NestedIterator(List<NestedInteger> nestedList) {
dfs(nestedList);
}
@Override
public Integer next() {
return nums.get(++i);
}
@Override
public boolean hasNext() {
return i + 1 < nums.size();
}
private void dfs(List<NestedInteger> ls) {
for (var x : ls) {
if (x.isInteger()) {
nums.add(x.getInteger());
} else {
dfs(x.getList());
}
}
}
}
/**
* Your NestedIterator object will be instantiated and called as such:
* NestedIterator i = new NestedIterator(nestedList);
* while (i.hasNext()) v[f()] = i.next();
*//**
* // This is the interface that allows for creating nested lists.
* // You should not implement it, or speculate about its implementation
* class NestedInteger {
* public:
* // Return true if this NestedInteger holds a single integer, rather than a nested list.
* bool isInteger() const;
*
* // Return the single integer that this NestedInteger holds, if it holds a single integer
* // The result is undefined if this NestedInteger holds a nested list
* int getInteger() const;
*
* // Return the nested list that this NestedInteger holds, if it holds a nested list
* // The result is undefined if this NestedInteger holds a single integer
* const vector<NestedInteger> &getList() const;
* };
*/
class NestedIterator {
public:
NestedIterator(vector<NestedInteger>& nestedList) {
auto dfs = [&](this auto&& dfs, vector<NestedInteger>& ls) -> void {
for (auto& x : ls) {
if (x.isInteger()) {
nums.push_back(x.getInteger());
} else {
dfs(x.getList());
}
}
};
dfs(nestedList);
}
int next() {
return nums[++i];
}
bool hasNext() {
return i + 1 < nums.size();
}
private:
vector<int> nums;
int i = -1;
};
/**
* Your NestedIterator object will be instantiated and called as such:
* NestedIterator i(nestedList);
* while (i.hasNext()) cout << i.next();
*//**
* // This is the interface that allows for creating nested lists.
* // You should not implement it, or speculate about its implementation
* type NestedInteger struct {
* }
*
* // Return true if this NestedInteger holds a single integer, rather than a nested list.
* func (this NestedInteger) IsInteger() bool {}
*
* // Return the single integer that this NestedInteger holds, if it holds a single integer
* // The result is undefined if this NestedInteger holds a nested list
* // So before calling this method, you should have a check
* func (this NestedInteger) GetInteger() int {}
*
* // Set this NestedInteger to hold a single integer.
* func (n *NestedInteger) SetInteger(value int) {}
*
* // Set this NestedInteger to hold a nested list and adds a nested integer to it.
* func (this *NestedInteger) Add(elem NestedInteger) {}
*
* // Return the nested list that this NestedInteger holds, if it holds a nested list
* // The list length is zero if this NestedInteger holds a single integer
* // You can access NestedInteger's List element directly if you want to modify it
* func (this NestedInteger) GetList() []*NestedInteger {}
*/
type NestedIterator struct {
nums []int
i int
}
func Constructor(nestedList []*NestedInteger) *NestedIterator {
var dfs func([]*NestedInteger)
nums := []int{}
i := -1
dfs = func(ls []*NestedInteger) {
for _, x := range ls {
if x.IsInteger() {
nums = append(nums, x.GetInteger())
} else {
dfs(x.GetList())
}
}
}
dfs(nestedList)
return &NestedIterator{nums, i}
}
func (this *NestedIterator) Next() int {
this.i++
return this.nums[this.i]
}
func (this *NestedIterator) HasNext() bool {
return this.i+1 < len(this.nums)
}/**
* // This is the interface that allows for creating nested lists.
* // You should not implement it, or speculate about its implementation
* class NestedInteger {
* If value is provided, then it holds a single integer
* Otherwise it holds an empty nested list
* constructor(value?: number) {
* ...
* };
*
* Return true if this NestedInteger holds a single integer, rather than a nested list.
* isInteger(): boolean {
* ...
* };
*
* Return the single integer that this NestedInteger holds, if it holds a single integer
* Return null if this NestedInteger holds a nested list
* getInteger(): number | null {
* ...
* };
*
* Set this NestedInteger to hold a single integer equal to value.
* setInteger(value: number) {
* ...
* };
*
* Set this NestedInteger to hold a nested list and adds a nested integer elem to it.
* add(elem: NestedInteger) {
* ...
* };
*
* Return the nested list that this NestedInteger holds,
* or an empty list if this NestedInteger holds a single integer
* getList(): NestedInteger[] {
* ...
* };
* };
*/
class NestedIterator {
private nums: number[] = [];
private i = -1;
constructor(nestedList: NestedInteger[]) {
const dfs = (ls: NestedInteger[]) => {
for (const x of ls) {
if (x.isInteger()) {
this.nums.push(x.getInteger());
} else {
dfs(x.getList());
}
}
};
dfs(nestedList);
}
hasNext(): boolean {
return this.i + 1 < this.nums.length;
}
next(): number {
return this.nums[++this.i];
}
}
/**
* Your ParkingSystem object will be instantiated and called as such:
* var obj = new NestedIterator(nestedList)
* var a: number[] = []
* while (obj.hasNext()) a.push(obj.next());
*/// #[derive(Debug, PartialEq, Eq)]
// pub enum NestedInteger {
// Int(i32),
// List(Vec<NestedInteger>)
// }
struct NestedIterator {
nums: Vec<i32>,
i: usize,
}
/**
* `&self` means the method takes an immutable reference.
* If you need a mutable reference, change it to `&mut self` instead.
*/
impl NestedIterator {
fn new(nested_list: Vec<NestedInteger>) -> Self {
let mut nums = Vec::new();
Self::dfs(&nested_list, &mut nums);
NestedIterator { nums, i: 0 }
}
fn next(&mut self) -> i32 {
let result = self.nums[self.i];
self.i += 1;
result
}
fn has_next(&self) -> bool {
self.i < self.nums.len()
}
fn dfs(nested_list: &Vec<NestedInteger>, nums: &mut Vec<i32>) {
for ni in nested_list {
match ni {
NestedInteger::Int(x) => nums.push(*x),
NestedInteger::List(list) => Self::dfs(list, nums),
}
}
}
}