easy

ProblemYou are given an integer array nums consisting of n elements, and an integer k. Find a contiguous subarray whose length is equal to k that has the maximum average value and return this value. Any answer with a calculation error less than 10-5 will be accepted. Example 1: 1234Input: nums = [1,12,-5,-6,50,3], k = 4Output: 12.75000Explanation: Maximum average is (12 - 5 - 6 + 50) / 4 = 51 / 4 = 12.75 Example 2: 123Input: nums = [5], k = 1Output: 5.00000 Constraints: n == nums.length 1 < ...

ProblemGiven an integer array nums, move all 0‘s to the end of it while maintaining the relative order of the non-zero elements. Note that you must do this in-place without making a copy of the array. Example 1: 123Input: nums = [0,1,0,3,12]Output: [1,3,12,0,0] Example 2: 123Input: nums = [0]Output: [0] Constraints: 1 <= nums.length <= 10^4 2^31 <= nums[i] <= 2^31 - 1 Follow up: Could you minimize the total number of operations done? Solve123456789101112class Solution: def mov ...

ProblemYou are given two strings word1 and word2. Merge the strings by adding letters in alternating order, starting with word1. If a string is longer than the other, append the additional letters onto the end of the merged string. Return the merged string. Example 1: 1234567Input: word1 = "abc", word2 = "pqr"Output: "apbqcr"Explanation: The merged string will be merged as so:word1: a b cword2: p q rmerged: a p b q c r Example 2: 1234567Input: word1 = & ...

ProblemGiven an array of integers nums and an integer target, return indices of the two numbers such that they add up to target. You may assume that each input would have exactly one solution, and you may not use the same element twice. You can return the answer in any order. Example 1: 1234Input: nums = [2,7,11,15], target = 9Output: [0,1]Explanation: Because nums[0] + nums[1] == 9, we return [0, 1]. Example 2: 123Input: nums = [3,2,4], target = 6Output: [1,2] Example 3: 123Input: nums = [3,3 ...

ProblemWrite an algorithm to determine if a number n is happy. A happy number is a number defined by the following process: Starting with any positive integer, replace the number by the sum of the squares of its digits. Repeat the process until the number equals 1 (where it will stay), or it loops endlessly in a cycle which does not include 1. Those numbers for which this process ends in 1 are happy. Return true if n is a happy number, and false if not. Example 1: 12345678Input: n = 19Output: ...

ProblemGiven the root of a Binary Search Tree (BST), return the minimum absolute difference between the values of any two different nodes in the tree. Example 1: !https://assets.leetcode.com/uploads/2021/02/05/bst1.jpg 123Input: root = [4,2,6,1,3]Output: 1 Example 2: !https://assets.leetcode.com/uploads/2021/02/05/bst2.jpg 123Input: root = [1,0,48,null,null,12,49]Output: 1 Constraints: The number of nodes in the tree is in the range [2, 10^4]. 0 <= Node.val <= 10^5 Solve法一由於有有序性質、且正整 ...

ProblemGiven an integer x, return true if x is a palindrome , and false otherwise 1234PalindromeAn integer is a palindrome when it reads the same forward and backward.For example, 121 is a palindrome while 123 is not . Example 1: 1234Input: x = 121Output: trueExplanation: 121 reads as 121 from left to right and from right to left. Example 2: 1234Input: x = -121Output: falseExplanation: From left to right, it reads -121. From right to left, it becomes 121-. Therefore it is not a palindrome. Ex ...

ProblemReverse bits of a given 32 bits unsigned integer. Note: Note that in some languages, such as Java, there is no unsigned integer type. In this case, both input and output will be given as a signed integer type. They should not affect your implementation, as the integer’s internal binary representation is the same, whether it is signed or unsigned. In Java, the compiler represents the signed integers using 2’s complement notation. Therefore, in Example 2 above, the input represents the sig ...

ProblemGiven two binary strings a and b, return their sum as a binary string. Example 1: 123Input: a = "11", b = "1"Output: "100" Example 2: 123Input: a = "1010", b = "1011"Output: "10101" Constraints: 1 <= a.length, b.length <= 10^4 a and b consist only of '0' or '1' characters. Each string does not contain leading zeros except for the zero itself. Solve123456789101112131415161718192021222324class Solution: ...

ProblemGiven a sorted array of distinct integers and a target value, return the index if the target is found. If not, return the index where it would be if it were inserted in order. You must write an algorithm with O(log n) runtime complexity. Example 1: 123Input: nums = [1,3,5,6], target = 5Output: 2 Example 2: 123Input: nums = [1,3,5,6], target = 2Output: 1 Example 3: 123Input: nums = [1,3,5,6], target = 7Output: 4 Constraints: 1 <= nums.length <= 10^4 10^4 <= nums[i] <= 10^4 ...