A valid encoding of an array of words is any reference string s and array of indices indices such that:
- words.length == indices.length
- The reference string s ends with the ‘#’ character.
- For each index indices[i], the substring of s starting from indices[i] and up to (but not including) the next ‘#’ character is equal to words[i].
Given an array of words, return the length of the shortest reference string s possible of any valid encoding of words.
637. Average of Levels in Binary Tree
Given a non-empty binary tree, return the average value of the nodes on each level in the form of an array.
Note:
The range of node’s value is in the range of 32-bit signed integer.
160. Intersection of Two Linked Lists
Write a program to find the node at which the intersection of two singly linked lists begins.
Given a nested list of integers represented as a string, implement a parser to deserialize it.
Each element is either an integer, or a list — whose elements may also be integers or other lists.
Note: You may assume that the string is well-formed:
- String is non-empty.
- String does not contain white spaces.
- String contains only digits 0-9, [, - ,, ].
Given an array nums containing n distinct numbers in the range [0, n], return the only number in the range that is missing from the array.
Follow up: Could you implement a solution using only O(1) extra space complexity and O(n) runtime complexity?
We have an array arr of non-negative integers.
For every (contiguous) subarray sub = [arr[i], arr[i + 1], …, arr[j]] (with i <= j), we take the bitwise OR of all the elements in sub, obtaining a result arr[i] | arr[i + 1] | … | arr[j].
Return the number of possible results. Results that occur more than once are only counted once in the final answer
918. Maximum Sum Circular Subarray
Given a circular array C of integers represented by A, find the maximum possible sum of a non-empty subarray of C.
Here, a circular array means the end of the array connects to the beginning of the array. (Formally, C[i] = A[i] when 0 <= i < A.length, and C[i+A.length] = C[i] when i >= 0.)
Also, a subarray may only include each element of the fixed buffer A at most once. (Formally, for a subarray C[i], C[i+1], …, C[j], there does not exist i <= k1, k2 <= j with k1 % A.length = k2 % A.length.)
You have a set of integers s, which originally contains all the numbers from 1 to n. Unfortunately, due to some error, one of the numbers in s got duplicated to another number in the set, which results in repetition of one number and loss of another number.
You are given an integer array nums representing the data status of this set after the error.
Find the number that occurs twice and the number that is missing and return them in the form of an array.
522. Longest Uncommon Subsequence II
Given a list of strings, you need to find the longest uncommon subsequence among them. The longest uncommon subsequence is defined as the longest subsequence of one of these strings and this subsequence should not be any subsequence of the other strings.
A subsequence is a sequence that can be derived from one sequence by deleting some characters without changing the order of the remaining elements. Trivially, any string is a subsequence of itself and an empty string is a subsequence of any string.
The input will be a list of strings, and the output needs to be the length of the longest uncommon subsequence. If the longest uncommon subsequence doesn’t exist, return -1.