[LeetCode] Clone N-ary Tree

1490. Clone N-ary Tree

Given a root of an N-ary tree, return a deep copy (clone) of the tree.

Each node in the n-ary tree contains a val (int) and a list (List[Node]) of its children.

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class Node {
public int val;
public List<Node> children;
}

Nary-Tree input serialization is represented in their level order traversal, each group of children is separated by the null value (See examples).

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[LeetCode] Add Two Polynomials Represented as Linked Lists

1634. Add Two Polynomials Represented as Linked Lists

A polynomial linked list is a special type of linked list where every node represents a term in a polynomial expression.

Each node has three attributes:

  • coefficient: an integer representing the number multiplier of the term. The coefficient of the term 9x4 is 9.
  • power: an integer representing the exponent. The power of the term 9x4 is 4.
  • next: a pointer to the next node in the list, or null if it is the last node of the list.

For example, the polynomial 5x3 + 4x - 7 is represented by the polynomial linked list illustrated below:

The polynomial linked list must be in its standard form: the polynomial must be in strictly descending order by its power value. Also, terms with a coefficient of 0 are omitted.

Given two polynomial linked list heads, poly1 and poly2, add the polynomials together and return the head of the sum of the polynomials.

PolyNode format:

The input/output format is as a list of n nodes, where each node is represented as its [coefficient, power]. For example, the polynomial 5x3 + 4x - 7 would be represented as: [[5,3],[4,1],[-7,0]].

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[LeetCode] N-ary Tree Preorder Traversal

589. N-ary Tree Preorder Traversal

Given the root of an n-ary tree, return the preorder traversal of its nodes’ values.

Nary-Tree input serialization is represented in their level order traversal. Each group of children is separated by the null value (See examples)

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[LeetCode] Counting Bits

338. Counting Bits

Given an integer n, return an array ans of length n + 1 such that for each i (0 <= i <= n), ans[i] is the number of 1’s in the binary representation of i.

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[LeetCode] Next Greater Element I

496. Next Greater Element I

The next greater element of some element x in an array is the first greater element that is to the right of x in the same array.

You are given two distinct 0-indexed integer arrays nums1 and nums2, where nums1 is a subset of nums2.

For each 0 <= i < nums1.length, find the index j such that nums1[i] == nums2[j] and determine the next greater element of nums2[j] in nums2. If there is no next greater element, then the answer for this query is -1.

Return an array ans of length nums1.length such that ans[i] is the next greater element as described above.

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[LeetCode] Synonymous Sentences

1258. Synonymous Sentences

You are given a list of equivalent string pairs synonyms where synonyms[i] = [si, ti] indicates that si and ti are equivalent strings. You are also given a sentence text.

Return all possible synonymous sentences sorted lexicographically.

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