537. Complex Number Multiplication
A complex number can be represented as a string on the form “real+imaginaryi” where:
- real is the real part and is an integer in the range [-100, 100].
- imaginary is the imaginary part and is an integer in the range [-100, 100].
- i2 == -1.
Given two complex numbers num1 and num2 as strings, return a string of the complex number that represents their multiplications.
1676. Lowest Common Ancestor of a Binary Tree IV
Given the root of a binary tree and an array of TreeNode objects nodes, return the lowest common ancestor (LCA) of all the nodes in nodes. All the nodes will exist in the tree, and all values of the tree’s nodes are unique.
Extending the definition of LCA on Wikipedia: “The lowest common ancestor of n nodes p1, p2, …, pn in a binary tree T is the lowest node that has every pi as a descendant (where we allow a node to be a descendant of itself) for every valid i”. A descendant of a node x is a node y that is on the path from node x to some leaf node.
A maximum tree is a tree where every node has a value greater than any other value in its subtree.
You are given the root of a maximum binary tree and an integer val.
Just as in the previous problem, the given tree was constructed from a list a (root = Construct(a)) recursively with the following Construct(a) routine:
- If a is empty, return null.
- Otherwise, let a[i] be the largest element of a. Create a root node with the value a[i].
- The left child of root will be Construct([a[0], a[1], …, a[i - 1]]).
- The right child of root will be Construct([a[i + 1], a[i + 2], …, a[a.length - 1]]).
- Return root.
Note that we were not given a directly, only a root node root = Construct(a).
Suppose b is a copy of a with the value val appended to it. It is guaranteed that b has unique values.
Return Construct(b).
Given a list of strings words and a string pattern, return a list of words[i] that match pattern. You may return the answer in any order.
A word matches the pattern if there exists a permutation of letters p so that after replacing every letter x in the pattern with p(x), we get the desired word.
Recall that a permutation of letters is a bijection from letters to letters: every letter maps to another letter, and no two letters map to the same letter.