Easy

1455. Check If a Word Occurs As a Prefix of Any Word in a Sentence Given a sentence that consists of some words separated by a single space, and a searchWord. You have to check if searchWord is a prefix of any word in sentence. Return the index of the word in sentence where searchWord is a prefix of this word (1-indexed). If searchWord is a prefix of more than one word, return the index of the first word (minimum index). If there is no such word return -1. ...

1844. Replace All Digits with Characters You are given a 0-indexed string s that has lowercase English letters in its even indices and digits in its odd indices. There is a function shift(c, x), where c is a character and x is a digit, that returns the xth character after c. For example, shift(‘a’, 5) = ‘f’ and shift(‘x’, 0) = ‘x’. For every odd index i, you want to replace the digit s[i] with shift(s[i-1], s[i]). ...

859. Buddy Strings Given two strings a and b, return true if you can swap two letters in a so the result is equal to b, otherwise, return false. Swapping letters is defined as taking two indices i and j (0-indexed) such that i != j and swapping the characters at a[i] and a[j]. For example, swapping at indices 0 and 2 in “abcd” results in “cbad”. Example 1: Input: a = "ab", b = "ba" Output: true Explanation: You can swap a[0] = 'a' and a[1] = 'b' to get "ba", which is equal to b. Example 2: Input: a = "ab", b = "ab" Output: false Explanation: The only letters you can swap are a[0] = 'a' and a[1] = 'b', which results in "ba" != b. Example 3: Input: a = "aa", b = "aa" Output: true Explanation: You can swap a[0] = 'a' and a[1] = 'a' to get "aa", which is equal to b. Example 4: Input: a = "aaaaaaabc", b = "aaaaaaacb" Output: true Constraints: ...

720. Longest Word in Dictionary Given an array of strings words representing an English Dictionary, return the longest word in words that can be built one character at a time by other words in words. If there is more than one possible answer, return the longest word with the smallest lexicographical order. If there is no answer, return the empty string. Example 1: Input: words = ["w","wo","wor","worl","world"] Output: "world" Explanation: The word "world" can be built one character at a time by "w", "wo", "wor", and "worl". Example 2: Input: words = ["a","banana","app","appl","ap","apply","apple"] Output: "apple" Explanation: Both "apply" and "apple" can be built from other words in the dictionary. However, "apple" is lexicographically smaller than "apply". Constraints: ...

28. Implement strStr() Implement strStr(). Return the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack. Clarification: What should we return when needle is an empty string? This is a great question to ask during an interview. For the purpose of this problem, we will return 0 when needle is an empty string. This is consistent to C’s strstr() and Java’s indexOf(). ...

1828. Queries on Number of Points Inside a Circle You are given an array points where points[i] = [xi, yi] is the coordinates of the ith point on a 2D plane. Multiple points can have the same coordinates. You are also given an array queries where queries[j] = [xj, yj, rj] describes a circle centered at (xj, yj) with a radius of rj. For each query queries[j], compute the number of points inside the jth circle. Points on the border of the circle are considered inside. ...

1365. How Many Numbers Are Smaller Than the Current Number Given the array nums, for each nums[i] find out how many numbers in the array are smaller than it. That is, for each nums[i] you have to count the number of valid j’s such that j != i and nums[j] < nums[i]. Return the answer in an array. Example 1: Input: nums = [8,1,2,2,3] Output: [4,0,1,1,3] Explanation: For nums[0]=8 there exist four smaller numbers than it (1, 2, 2 and 3). For nums[1]=1 does not exist any smaller number than it. For nums[2]=2 there exist one smaller number than it (1). For nums[3]=2 there exist one smaller number than it (1). For nums[4]=3 there exist three smaller numbers than it (1, 2 and 2). Example 2: Input: nums = [6,5,4,8] Output: [2,1,0,3] Example 3: Input: nums = [7,7,7,7] Output: [0,0,0,0] Constraints: ...

1827. Minimum Operations to Make the Array Increasing You are given an integer array nums (0-indexed). In one operation, you can choose an element of the array and increment it by 1. For example, if nums = [1,2,3], you can choose to increment nums[1] to make nums = [1,3,3]. Return the minimum number of operations needed to make nums strictly increasing. An array nums is strictly increasing if nums[i] < nums[i+1] for all 0 <= i < nums.length - 1. An array of length 1 is trivially strictly increasing. ...

1779. Find Nearest Point That Has the Same X or Y Coordinate You are given two integers, x and y, which represent your current location on a Cartesian grid: (x, y). You are also given an array points where each points[i] = [ai, bi] represents that a point exists at (ai, bi). A point is valid if it shares the same x-coordinate or the same y-coordinate as your location. Return the index (0-indexed) of the valid point with the smallest Manhattan distance from your current location. If there are multiple, return the valid point with the smallest index. If there are no valid points, return -1. ...

1379. Find a Corresponding Node of a Binary Tree in a Clone of That Tree Given two binary trees original and cloned and given a reference to a node target in the original tree. The cloned tree is a copy of the original tree. Return a reference to the same node in the cloned tree. Note that you are not allowed to change any of the two trees or the target node and the answer must be a reference to a node in the cloned tree. ...