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Given an array of integers nums sorted in non-decreasing order, find the starting and ending position of a given target value. If target is not found in the array, return [-1, -1]. You must write an algorithm with O(log n) runtime complexity. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Example 1: Input: nums = [5,7,7,8,8,10], target = 8 Output: [3,4] Example 2: Input: nums = [5,7,7,8,8,10], target = 6 Output: [-1,-1] Example 3: Input: nums = [], target = 0 Output: [-1,-1] Constraints:...

Given two strings s and t of length N, find the maximum number of possible matching pairs in strings s and t after swapping exactly two characters within s. A swap is switching s[i] and s[j], where s[i] and s[j] denotes the character that is present at the ith and jth index of s, respectively. The matching pairs of the two strings are defined as the number of indices for which s[i] and t[i] are equal....

Pair Sums Given a list of n integers arr[0..(n-1)], determine the number of different pairs of elements within it which sum to k. If an integer appears in the list multiple times, each copy is considered to be different; that is, two pairs are considered different if one pair includes at least one array index which the other doesn’t, even if they include the same values. Signature int numberOfWays(int[] arr, int k) Input n is in the range [1, 100,000]....

Android devices have a special lock screen with a 3 x 3 grid of dots. Users can set an “unlock pattern” by connecting the dots in a specific sequence, forming a series of joined line segments where each segment’s endpoints are two consecutive dots in the sequence. A sequence of k dots is a valid unlock pattern if both of the following are true: All the dots in the sequence are distinct....

You are given an array arr of N integers. For each index i, you are required to determine the number of contiguous subarrays that fulfill the following conditions: The value at index i must be the maximum element in the contiguous subarrays, and These contiguous subarrays must either start from or end on index i. Signature int[] countSubarrays(int[] arr) Input Array arr is a non-empty list of unique integers that range between 1 to 1,000,000,000 Size N is between 1 and 1,000,000 Output An array where each index i contains an integer denoting the maximum number of contiguous subarrays of arr[i]...

Given two binary search trees root1 and root2. Return a list containing all the integers from both trees sorted in ascending order. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 Example 1: Input: root1 = [2,1,4], root2 = [1,0,3] Output: [0,1,1,2,3,4] Example 2: Input: root1 = [0,-10,10], root2 = [5,1,7,0,2] Output: [-10,0,0,1,2,5,7,10] Example 3: Input: root1 = [], root2 = [5,1,7,0,2] Output: [0,1,2,5,7] Example 4: Input: root1 = [0,-10,10], root2 = [] Output: [-10,0,10] 1 2 3 4 Example 5: Input: root1 = [1,null,8], root2 = [8,1] Output: [1,1,8,8] Constraints:...

Implement the BSTIterator class that represents an iterator over the in-order traversal of a binary search tree (BST): BSTIterator(TreeNode root) Initializes an object of the BSTIterator class. The root of the BST is given as part of the constructor. The pointer should be initialized to a non-existent number smaller than any element in the BST. boolean hasNext() Returns true if there exists a number in the traversal to the right of the pointer, otherwise returns false....

An integer array is called arithmetic if it consists of at least three elements and if the difference between any two consecutive elements is the same. For example, [1,3,5,7,9], [7,7,7,7], and [3,-1,-5,-9] are arithmetic sequences. Given an integer array nums, return the number of arithmetic subarrays of nums. A subarray is a contiguous subsequence of the array. 1 2 3 4 5 6 7 8 9 10 Example 1: Input: nums = [1,2,3,4] Output: 3 Explanation: We have 3 arithmetic slices in nums: [1, 2, 3], [2, 3, 4] and [1,2,3,4] itself....

Design a time-based key-value data structure that can store multiple values for the same key at different time stamps and retrieve the key’s value at a certain timestamp. Implement the TimeMap class: TimeMap() Initializes the object of the data structure. void set(String key, String value, int timestamp) Stores the key key with the value value at the given time timestamp. String get(String key, int timestamp) Returns a value such that set was called previously, with timestamp_prev <= timestamp....

Given the root of a binary tree, return the lowest common ancestor of its deepest leaves. Recall that: The node of a binary tree is a leaf if and only if it has no children The depth of the root of the tree is 0. if the depth of a node is d, the depth of each of its children is d + 1. The lowest common ancestor of a set S of nodes, is the node A with the largest depth such that every node in S is in the subtree with root A....

We have a wooden plank of the length n units. Some ants are walking on the plank, each ant moves with speed 1 unit per second. Some of the ants move to the left, the other move to the right. When two ants moving in two different directions meet at some point, they change their directions and continue moving again. Assume changing directions doesn’t take any additional time. When an ant reaches one end of the plank at a time t, it falls out of the plank imediately....

Given an array nums and an integer target. Return the maximum number of non-empty non-overlapping subarrays such that the sum of values in each subarray is equal to target. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 Example 1: Input: nums = [1,1,1,1,1], target = 2 Output: 2 Explanation: There are 2 non-overlapping subarrays [1,1,1,1,1] with sum equals to target(2)....

We can represent a sentence as an array of words, for example, the sentence “I am happy with leetcode” can be represented as arr = [“I”,“am”,happy",“with”,“leetcode”]. Given two sentences sentence1 and sentence2 each represented as a string array and given an array of string pairs similarPairs where similarPairs[i] = [xi, yi] indicates that the two words xi and yi are similar. Return true if sentence1 and sentence2 are similar, or false if they are not similar....

Given an array nums of integers, return the length of the longest arithmetic subsequence in nums. Recall that a subsequence of an array nums is a list nums[i1], nums[i2], …, nums[ik] with 0 <= i1 < i2 < … < ik <= nums.length - 1, and that a sequence seq is arithmetic if seq[i+1] - seq[i] are all the same value (for 0 <= i < seq.length - 1)....

Given the root of a binary tree, determine if it is a complete binary tree. In a complete binary tree, every level, except possibly the last, is completely filled, and all nodes in the last level are as far left as possible. It can have between 1 and 2h nodes inclusive at the last level h. 1 2 3 4 5 Example 1: Input: root = [1,2,3,4,5,6] Output: true Explanation: Every level before the last is full (ie....