You’re given a nested list of integers. Each element is either an integer or a list whose elements may also be integers or other integer lists. Your task is to implement an iterator to flatten the nested list.
You will have to implement the Nested Iterator class. This class has the following functions:
Constraints
We’ll use a stack to solve this problem. The stack will be used to store the integer and list of integers on the iterator object. We’ll push all the nested list data in the stack in reverse order in the constructor. The elements are pushed in reverse order because the iterator is implemented using a stack. In order to process the nested list correctly, the elements need to be accessed in the order they appear in the original nested list.
Here is how we implement the NestedIterator class methods to solve the above problem:
The constructor initializes an empty stack of NestedInteger objects.
The constructor iterates through the input nestedList, starting from the last element to the first element (reverse order). It pushes each element onto the stack using stack.push().
hasNext() method:The hasNext() method checks if there is a next integer to return from the stack, iterating through nested lists if necessary.
The top element of the stack is retrieved using stack.peek().
The top element is checked using the method top.isInteger():
If it is an integer, the method returns TRUE because the next element is an integer.
The top element must be a nested list if it is not an integer. In this case:
The top element is popped from the stack using stack.pop().
The list is retrieved using top.getList().
The elements of this nested list are pushed onto the stack in reverse order using stack.push(). This ensures that the first element of the nested list will be processed first.
If the stack is empty, the method returns FALSE. ...
next() method:You’re given a nested list of integers. Each element is either an integer or a list whose elements may also be integers or other integer lists. Your task is to implement an iterator to flatten the nested list.
You will have to implement the Nested Iterator class. This class has the following functions:
Constraints
We’ll use a stack to solve this problem. The stack will be used to store the integer and list of integers on the iterator object. We’ll push all the nested list data in the stack in reverse order in the constructor. The elements are pushed in reverse order because the iterator is implemented using a stack. In order to process the nested list correctly, the elements need to be accessed in the order they appear in the original nested list.
Here is how we implement the NestedIterator class methods to solve the above problem:
The constructor initializes an empty stack of NestedInteger objects.
The constructor iterates through the input nestedList, starting from the last element to the first element (reverse order). It pushes each element onto the stack using stack.push().
hasNext() method:The hasNext() method checks if there is a next integer to return from the stack, iterating through nested lists if necessary.
The top element of the stack is retrieved using stack.peek().
The top element is checked using the method top.isInteger():
If it is an integer, the method returns TRUE because the next element is an integer.
The top element must be a nested list if it is not an integer. In this case:
The top element is popped from the stack using stack.pop().
The list is retrieved using top.getList().
The elements of this nested list are pushed onto the stack in reverse order using stack.push(). This ensures that the first element of the nested list will be processed first.
If the stack is empty, the method returns FALSE. ...
next() method: