Given a pattern and a string s, return true if s matches the pattern. A string s matches a pattern if there is some bijective mapping of single characters to strings such that if each character in pattern is replaced by the string it maps to, then the resulting string is s. A bijective mapping means that no two characters map to the same string, and no character maps to two different strings....
You are given an array routes representing bus routes where routes[i] is a bus route that the ith bus repeats forever. For example, if routes[0] = [1, 5, 7], this means that the 0th bus travels in the sequence 1 -> 5 -> 7 -> 1 -> 5 -> 7 -> 1 -> … forever. You will start at the bus stop source (You are not on any bus initially), and you want to go to the bus stop target....
We can shift a string by shifting each of its letters to its successive letter. For example, “abc” can be shifted to be “bcd”. We can keep shifting the string to form a sequence. For example, we can keep shifting “abc” to form the sequence: “abc” -> “bcd” -> … -> “xyz”. Given an array of strings strings, group all strings[i] that belong to the same shifting sequence. You may return the answer in any order....
Given two strings s and t of lengths m and n respectively, return the minimum window substring of s such that every character in t (including duplicates) is included in the window. If there is no such substring, return the empty string “”. The testcases will be generated such that the answer is unique. A substring is a contiguous sequence of characters within the string. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 Example 1: Input: s = "ADOBECODEBANC", t = "ABC" Output: "BANC" Explanation: The minimum window substring "BANC" includes 'A', 'B', and 'C' from string t....
A parentheses string is valid if and only if: It is the empty string, It can be written as AB (A concatenated with B), where A and B are valid strings, or It can be written as (A), where A is a valid string. You are given a parentheses string s. In one move, you can insert a parenthesis at any position of the string. For example, if s = “()))”, you can insert an opening parenthesis to be “(()))” or a closing parenthesis to be “())))”....
Given the root of a binary tree, return all root-to-leaf paths in any order. A leaf is a node with no children. 1 2 3 4 5 6 7 8 9 Example 1: Input: root = [1,2,3,null,5] Output: ["1->2->5","1->3"] Example 2: Input: root = [1] Output: ["1"] Constraints: The number of nodes in the tree is in the range [1, 100]. -100 <= Node.val <= 100 Solution 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 /** * Definition for a binary tree node....
Given a collection of numbers, nums, that might contain duplicates, return all possible unique permutations in any order. 1 2 3 4 5 6 7 8 9 10 11 12 Example 1: Input: nums = [1,1,2] Output: [[1,1,2], [1,2,1], [2,1,1]] Example 2: Input: nums = [1,2,3] Output: [[1,2,3],[1,3,2],[2,1,3],[2,3,1],[3,1,2],[3,2,1]] Constraints: 1 <= nums.length <= 8 -10 <= nums[i] <= 10 Solution 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 class Solution { public List<List<Integer>> permuteUnique(int[] nums) { List<List<Integer>> res = new ArrayList<>(); permuteAt(0, nums, res); return res; } void permuteAt(int i, int[] nums, List<List<Integer>> res) { if (i == nums....
Given two strings s and t, return true if they are both one edit distance apart, otherwise return false. A string s is said to be one distance apart from a string t if you can: Insert exactly one character into s to get t. Delete exactly one character from s to get t. Replace exactly one character of s with a different character to get t. 1 2 3 4 5 Example 1: Input: s = "ab", t = "acb" Output: true Explanation: We can insert 'c' into s to get t....
Given a string queryIP, return “IPv4” if IP is a valid IPv4 address, “IPv6” if IP is a valid IPv6 address or “Neither” if IP is not a correct IP of any type. A valid IPv4 address is an IP in the form “x1.x2.x3.x4” where 0 <= xi <= 255 and xi cannot contain leading zeros. For example, “192.168.1.1” and “192.168.1.0” are valid IPv4 addresses but “192.168.01.1”, while “192.168.1.00” and “192....
You are given two lists of closed intervals, firstList and secondList, where firstList[i] = [starti, endi] and secondList[j] = [startj, endj]. Each list of intervals is pairwise disjoint and in sorted order. Return the intersection of these two interval lists. A closed interval [a, b] (with a <= b) denotes the set of real numbers x with a <= x <= b. The intersection of two closed intervals is a set of real numbers that are either empty or represented as a closed interval....
A phrase is a palindrome if, after converting all uppercase letters into lowercase letters and removing all non-alphanumeric characters, it reads the same forward and backward. Alphanumeric characters include letters and numbers. Given a string s, return true if it is a palindrome, or false otherwise. 1 2 3 4 5 Example 1: Input: s = "A man, a plan, a canal: Panama" Output: true Explanation: "amanaplanacanalpanama" is a palindrome....
Given the root of a binary search tree, return a balanced binary search tree with the same node values. If there is more than one answer, return any of them. A binary search tree is balanced if the depth of the two subtrees of every node never differs by more than 1. 1 2 3 4 5 Example 1: Input: root = [1,null,2,null,3,null,4,null,null] Output: [2,1,3,null,null,null,4] Explanation: This is not the only correct answer, [3,1,4,null,2] is also correct....
Given a string num that contains only digits and an integer target, return all possibilities to insert the binary operators ‘+’, ‘-’, and/or ‘*’ between the digits of num so that the resultant expression evaluates to the target value. Note that operands in the returned expressions should not contain leading zeros. 1 2 3 4 5 Example 1: Input: num = "123", target = 6 Output: ["1*2*3","1+2+3"] Explanation: Both "1*2*3" and "1+2+3" evaluate to 6....
You are given two integer arrays nums1 and nums2, sorted in non-decreasing order, and two integers m and n, representing the number of elements in nums1 and nums2 respectively. Merge nums1 and nums2 into a single array sorted in non-decreasing order. The final sorted array should not be returned by the function, but instead be stored inside the array nums1. To accommodate this, nums1 has a length of m + n, where the first m elements denote the elements that should be merged, and the last n elements are set to 0 and should be ignored....
Given two sparse vectors, compute their dot product. Implement class SparseVector: SparseVector(nums) Initializes the object with the vector nums dotProduct(vec) Compute the dot product between the instance of SparseVector and vec A sparse vector is a vector that has mostly zero values, you should store the sparse vector efficiently and compute the dot product between two SparseVector. Follow up: What if only one of the vectors is sparse? 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 Example 1: Input: nums1 = [1,0,0,2,3], nums2 = [0,3,0,4,0] Output: 8 Explanation: v1 = SparseVector(nums1) , v2 = SparseVector(nums2) v1....