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You are given two strings s and t. String t is generated by random shuffling string s and then add one more letter at a random position. Return the letter that was added to t. Example 1: Input: s = "abcd", t = "abcde" Output: "e" Explanation: 'e' is the letter that was added. Example 2: Input: s = "", t = "y" Output: "y" Example 3: Input: s = "a", t = "aa" Output: "a" Example 4: Input: s = "ae",..
A peak element is an element that is strictly greater than its neighbors. Given an integer array nums, find a peak element, and return its index. If the array contains multiple peaks, return the index to any of the peaks. You may imagine that nums[-1] = nums[n] = -∞. Example 1: Input: nums = [1,2,3,1] Output: 2 Explanation: 3 is a peak element and your function should return the index number 2. ..
You are given an array coordinates, coordinates[i] = [x, y], where [x, y] represents the coordinate of a point. Check if these points make a straight line in the XY plane. Example 1: Input: coordinates = [[1,2],[2,3],[3,4],[4,5],[5,6],[6,7]] Output: true Example 2: Input: coordinates = [[1,1],[2,2],[3,4],[4,5],[5,6],[7,7]] Output: false Constraints: 2
Every non-negative integer N has a binary representation. For example, 5 can be represented as "101" in binary, 11 as "1011" in binary, and so on. Note that except for N = 0, there are no leading zeroes in any binary representation. The complement of a binary representation is the number in binary you get when changing every 1 to a 0 and 0 to a 1. For example, the complement of "101" in binary i..
Given a singly linked list, group all odd nodes together followed by the even nodes. Please note here we are talking about the node number and not the value in the nodes. You should try to do it in place. The program should run in O(1) space complexity and O(nodes) time complexity. Example 1: Input: 1->2->3->4->5->NULL Output: 1->3->5->2->4->NULL Example 2: Input: 2->1->3->5->6->4->7->NULL Outpu..
Given an array of integers arr, return true if and only if it is a valid mountain array. Recall that arr is a mountain array if and only if: arr.length >= 3 There exists some i with 0 < i < arr.length - 1 such that: arr < arr < ... < arr[i - 1] < arr[i] arr[i] > arr[i + 1] > ... > arr[arr.length - 1] Example 1: Input: arr = [2,1] Output: false Example 2: Input: arr = [3,5,5] Output: false ..
Given an integer n and an integer start. Define an array nums where nums[i] = start + 2*i (0-indexed) and n == nums.length. Return the bitwise XOR of all elements of nums. Example 1: Input: n = 5, start = 0 Output: 8 Explanation: Array nums is equal to [0, 2, 4, 6, 8] where (0 ^ 2 ^ 4 ^ 6 ^ 8) = 8. Where "^" corresponds to bitwise XOR operator. Example 2: Input: n = 4, start = 3 Output: 8 Explan..
Given a positive integer num, output its complement number. The complement strategy is to flip the bits of its binary representation. Example 1: Input: num = 5 Output: 2 Explanation: The binary representation of 5 is 101 (no leading zero bits), and its complement is 010. So you need to output 2. Example 2: Input: num = 1 Output: 0 Explanation: The binary representation of 1 is 1 (no leading zero..
Given a string S, we can transform every letter individually to be lowercase or uppercase to create another string. Return a list of all possible strings we could create. You can return the output in any order. Example 1: Input: S = "a1b2" Output: ["a1b2","a1B2","A1b2","A1B2"] Example 2: Input: S = "3z4" Output: ["3z4","3Z4"] Example 3: Input: S = "12345" Output: ["12345"] Example 4: Input: S = ..
Given a positive integer num, write a function which returns True if num is a perfect square else False. Follow up: Do not use any built-in library function such as sqrt. Example 1: Input: num = 16 Output: true Example 2: Input: num = 14 Output: false Constraints: 1
International Morse Code defines a standard encoding where each letter is mapped to a series of dots and dashes, as follows: "a" maps to ".-", "b" maps to "-...", "c" maps to "-.-.", and so on. For convenience, the full table for the 26 letters of the English alphabet is given below: [".-","-...","-.-.","-..",".","..-.","--.","....","..",".---","-.-",".-..","--","-.","---",".--.","--.-",".-.","...
Given an array of integers nums, sort the array in increasing order based on the frequency of the values. If multiple values have the same frequency, sort them in decreasing order. Return the sorted array. Example 1: Input: nums = [1,1,2,2,2,3] Output: [3,1,1,2,2,2] Explanation: '3' has a frequency of 1, '1' has a frequency of 2, and '2' has a frequency of 3. Example 2: Input: nums = [2,3,1,3,2]..
In English, we have a concept called root, which can be followed by some other word to form another longer word - let's call this word successor. For example, when the root "an" is followed by the successor word "other", we can form a new word "another". Given a dictionary consisting of many roots and a sentence consisting of words separated by spaces, replace all the successors in the sentence ..
Given a sorted array nums, remove the duplicates in-place such that duplicates appeared at most twice and return the new length. Do not allocate extra space for another array; you must do this by modifying the input array in-place with O(1) extra memory. Clarification: Confused why the returned value is an integer, but your answer is an array? Note that the input array is passed in by reference,..
Given a sentence text (A sentence is a string of space-separated words) in the following format: First letter is in upper case. Each word in text are separated by a single space. Your task is to rearrange the words in text such that all words are rearranged in an increasing order of their lengths. If two words have the same length, arrange them in their original order. Return the new text follow..
You are given a string text of words that are placed among some number of spaces. Each word consists of one or more lowercase English letters and are separated by at least one space. It's guaranteed that text contains at least one word. Rearrange the spaces so that there is an equal number of spaces between every pair of adjacent words and that number is maximized. If you cannot redistribute all..
Given a non-empty, singly linked list with head node head, return a middle node of linked list. If there are two middle nodes, return the second middle node. Example 1: Input: [1,2,3,4,5] Output: Node 3 from this list (Serialization: [3,4,5]) The returned node has value 3. (The judge's serialization of this node is [3,4,5]). Note that we returned a ListNode object ans, such that: ans.val = 3, an..
We have two special characters. The first character can be represented by one bit 0. The second character can be represented by two bits (10 or 11). Now given a string represented by several bits. Return whether the last character must be a one-bit character or not. The given string will always end with a zero. Example 1: Input: bits = [1, 0, 0] Output: True Explanation: The only way to decode i..
Given an array A of integers, for each integer A[i] we may choose any x with -K
Given a word, you need to judge whether the usage of capitals in it is right or not. We define the usage of capitals in a word to be right when one of the following cases holds: All letters in this word are capitals, like "USA". All letters in this word are not capitals, like "leetcode". Only the first letter in this word is capital, like "Google". Otherwise, we define that this word doesn't use..
Write a function to delete a node in a singly-linked list. You will not be given access to the head of the list, instead you will be given access to the node to be deleted directly. It is guaranteed that the node to be deleted is not a tail node in the list. Example 1: Input: head = [4,5,1,9], node = 5 Output: [4,1,9] Explanation: You are given the second node with value 5, the linked list shoul..
A web developer needs to know how to design a web page's size. So, given a specific rectangular web page’s area, your job by now is to design a rectangular web page, whose length L and width W satisfy the following requirements: The area of the rectangular web page you designed must equal to the given target area. The width W should not be larger than the length L, which means L >= W. The differ..
The Hamming distance between two integers is the number of positions at which the corresponding bits are different. Given two integers x and y, calculate the Hamming distance. Note: 0 ≤ x, y < 231. Example: Input: x = 1, y = 4 Output: 2 Explanation: 1 (0 0 0 1) 4 (0 1 0 0) ↑ ↑ The above arrows point to positions where the corresponding bits are different. Soltuion class Solution: def hammingDist..
S and T are strings composed of lowercase letters. In S, no letter occurs more than once. S was sorted in some custom order previously. We want to permute the characters of T so that they match the order that S was sorted. More specifically, if x occurs before y in S, then x should occur before y in the returned string. Return any permutation of T (as a string) that satisfies this property. Exam..
Given a string S and a character C, return an array of integers representing the shortest distance from the character C in the string. Example 1: Input: S = "loveleetcode", C = 'e' Output: [3, 2, 1, 0, 1, 0, 0, 1, 2, 2, 1, 0] Note: S string length is in [1, 10000]. C is a single character, and guaranteed to be in string S. All letters in S and C are lowercase. 첫번째 시도 class Solution: def shortest..
Given an integer array arr, return the mean of the remaining integers after removing the smallest 5% and the largest 5% of the elements. Answers within 10-5 of the actual answer will be considered accepted. Example 1: Input: arr = [1,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,3] Output: 2.00000 Explanation: After erasing the minimum and the maximum values of this array, all elements are equal to 2, so ..
Given head which is a reference node to a singly-linked list. The value of each node in the linked list is either 0 or 1. The linked list holds the binary representation of a number. Return the decimal value of the number in the linked list. Example 1: Input: head = [1,0,1] Output: 5 Explanation: (101) in base 2 = (5) in base 10 Example 2: Input: head =  Output: 0 Example 3: Input: head = ..
Given an array nums of integers, return how many of them contain an even number of digits. Example 1: Input: nums = [12,345,2,6,7896] Output: 2 Explanation: 12 contains 2 digits (even number of digits). 345 contains 3 digits (odd number of digits). 2 contains 1 digit (odd number of digits). 6 contains 1 digit (odd number of digits). 7896 contains 4 digits (even number of digits). Therefore only ..
Given an array of unique integers salary where salary[i] is the salary of the employee i. Return the average salary of employees excluding the minimum and maximum salary. Example 1: Input: salary = [4000,3000,1000,2000] Output: 2500.00000 Explanation: Minimum salary and maximum salary are 1000 and 4000 respectively. Average salary excluding minimum and maximum salary is (2000+3000)/2= 2500 Examp..
Given two non-negative integers low and high. Return the count of odd numbers between low and high (inclusive). Example 1: Input: low = 3, high = 7 Output: 3 Explanation: The odd numbers between 3 and 7 are [3,5,7]. Example 2: Input: low = 8, high = 10 Output: 1 Explanation: The odd numbers between 8 and 10 are . Constraints: 0