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27 leetcode.com Excel Sheet Column Number Problem Solving Medium Given a string columnTitle that represents the column title as appears in an Excel sheet, return its corresponding column number. For example: A -> 1 B -> 2 C -> 3 ... Z -> 26 AA -> 27 AB -> 28 ...   Example 1: Input: columnTitle = "A" Output: 1 Example 2: Input: columnTitle = "AB" Output: 28 Example 3: Input: columnTitle = "ZY" Output: 701
26 leetcode.com Search Insert Position Problem Solving Easy Given 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: Input: nums = [1,3,5,6], target = 5 Output: 2 Example 2: Input: nums = [1,3,5,6], target = 2 Output: 1 Example 3: Input: nums = [1,3,5,6], target = 7 Output: 4
25 leetcode.com Majority Element Problem Solving Easy Given an array nums of size n, return the majority element. The majority element is the element that appears more than ⌊n / 2⌋ times. You may assume that the majority element always exists in the array.   Example 1: Input: nums = [3,2,3] Output: 3 Example 2: Input: nums = [2,2,1,1,1,2,2] Output: 2
24 leetcode.com Merge Sorted Array Problem Solving Easy 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. nums2 has a length of n.   Example 1: Input: nums1 = [1,2,3,0,0,0], m = 3, nums2 = [2,5,6], n = 3 Output: [1,2,2,3,5,6] Explanation: The arrays we are merging are [1,2,3] and [2,5,6]. The result of the merge is [1,2,2,3,5,6] with the underlined elements coming from nums1. Example 2: Input: nums1 = [1], m = 1, nums2 = [], n = 0 Output: [1] Explanation: The arrays we are merging are [1] and []. The result of the merge is [1]. Example 3: Input: nums1 = [0], m = 0, nums2 = [1], n = 1 Output: [1] Explanation: The arrays we are merging are [] and [1]. The result of the merge is [1]. Note that because m = 0, there are no elements in nums1. The 0 is only there to ensure the merge result can fit in nums1.  
23 leetcode.com Valid Parentheses Problem Solving Hard Given a string s containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid. An input string is valid if: Open brackets must be closed by the same type of brackets. Open brackets must be closed in the correct order. Every close bracket has a corresponding open bracket of the same type.   Example 1: Input: s = "()" Output: true Example 2: Input: s = "()[]{}" Output: true Example 3: Input: s = "(]" Output: false
19 leetcode.com Longest Common Prefix Problem Solving Medium Write a function to find the longest common prefix string amongst an array of strings. If there is no common prefix, return an empty string "".   Example 1: Input: strs = ["flower","flow","flight"] Output: "fl" Example 2: Input: strs = ["dog","racecar","car"] Output: "" Explanation: There is no common prefix among the input strings
18 leetcode.com Two Sum Problem Solving Easy Given 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: Input: nums = [2,7,11,15], target = 9 Output: [0,1] Explanation: Because nums[0] + nums[1] == 9, we return [0, 1]. Example 2: Input: nums = [3,2,4], target = 6 Output: [1,2] Example 3: Input: nums = [3,3], target = 6 Output: [0,1]
17 leetcode.com Roman to Integer Problem Solving Medium Roman numerals are represented by seven different symbols: I, V, X, L, C, D and M. Symbol Value I 1 V 5 X 10 L 50 C 100 D 500 M 1000 For example, 2 is written as II in Roman numeral, just two ones added together. 12 is written as XII, which is simply X + II. The number 27 is written as XXVII, which is XX + V + II. Roman numerals are usually written largest to smallest from left to right. However, the numeral for four is not IIII. Instead, the number four is written as IV. Because the one is before the five we subtract it making four. The same principle applies to the number nine, which is written as IX. There are six instances where subtraction is used: I can be placed before V (5) and X (10) to make 4 and 9.  X can be placed before L (50) and C (100) to make 40 and 90.  C can be placed before D (500) and M (1000) to make 400 and 900. Given a roman numeral, convert it to an integer.   Example 1: Input: s = "III" Output: 3 Explanation: III = 3. Example 2: Input: s = "LVIII" Output: 58 Explanation: L = 50, V= 5, III = 3. Example 3: Input: s = "MCMXCIV" Output: 1994 Explanation: M = 1000, CM = 900, XC = 90 and IV = 4.  
16 leetcode.com Palindrome Number Problem Solving Easy Given an integer x, return true if x is a palindrome, and false otherwise.   Example 1: Input: x = 121 Output: true Explanation: 121 reads as 121 from left to right and from right to left. Example 2: Input: x = -121 Output: false Explanation: From left to right, it reads -121. From right to left, it becomes 121-. Therefore it is not a palindrome. Example 3: Input: x = 10 Output: false Explanation: Reads 01 from right to left. Therefore it is not a palindrome.  
10 edabit.com Sastry Numbers Problem Solving Very easy In this challenge, you have to establish if a given integer n is a Sastry number. If the number resulting from the concatenation of an integer n with its successor is a perfect square, then n is a Sastry Number. Given a positive integer n, implement a function that returns true if n is a Sastry number, or false if it's not. Examples isSastry(183) ➞ true // Concatenation of n and its successor = 183184 // 183184 is a perfect square (428 ^ 2) isSastry(184) ➞ false // Concatenation of n and its successor = 184185 // 184185 is not a perfect square isSastry(106755) ➞ true // Concatenation of n and its successor = 106755106756 // 106755106756 is a perfect square (326734 ^ 2)
Results: 180