LeetCode
AtCoderのBeginner Contentに初参戦してみました。 結果は緑(こちらのページによれば "ソフトウェアエンジニアとして申し分ない実力です" のレベル)相当には後一歩及ばずというところ。まだまだ精進です。 さて、今日の問題。 https://leetcode.com/problems…
https://leetcode.com/problems/pascals-triangle/ Given a non-negative integer numRows, generate the first numRows of Pascal's triangle. In Pascal's triangle, each number is the sum of the two numbers directly above it. Example: パスカルの三…
https://leetcode.com/problems/path-sum-ii/ Given a binary tree and a sum, find all root-to-leaf paths where each path's sum equals the given sum. Note: A leaf is a node with no children. Example: Given the below binary tree and sum = 22, R…
https://leetcode.com/problems/path-sum/ Given a binary tree and a sum, determine if the tree has a root-to-leaf path such that adding up all the values along the path equals the given sum. Note: A leaf is a node with no children. Example: …
https://leetcode.com/problems/balanced-binary-tree/ Given a binary tree, determine if it is height-balanced. For this problem, a height-balanced binary tree is defined as: a binary tree in which the depth of the two subtrees of every node …
https://leetcode.com/problems/minimum-depth-of-binary-tree/ Given a binary tree, find its minimum depth. The minimum depth is the number of nodes along the shortest path from the root node down to the nearest leaf node. Note: A leaf is a n…
https://leetcode.com/problems/convert-sorted-array-to-binary-search-tree/ Given an array where elements are sorted in ascending order, convert it to a height balanced BST. For this problem, a height-balanced binary tree is defined as a bin…
https://leetcode.com/problems/binary-tree-level-order-traversal-ii/ Given a binary tree, return the bottom-up level order traversal of its nodes' values. (ie, from left to right, level by level from leaf to root). For example: Given binary…
https://leetcode.com/problems/maximum-depth-of-binary-tree/ Given a binary tree, find its maximum depth. The maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node. Note: A leaf is a n…
https://leetcode.com/problems/symmetric-tree/ Given a binary tree, check whether it is a mirror of itself (ie, symmetric around its center). For example, this binary tree [1,2,2,3,4,4,3] is symmetric: But the following [1,2,2,null,3,null,3…
https://leetcode.com/problems/same-tree/ Given two binary trees, write a function to check if they are the same or not. Two binary trees are considered the same if they are structurally identical and the nodes have the same value. LeetCode…
https://leetcode.com/problems/merge-sorted-array/ Given two sorted integer arrays nums1 and nums2, merge nums2 into nums1 as one sorted array. Note: The number of elements initialized in nums1 and nums2 are m and n respectively. You may as…
https://leetcode.com/problems/remove-duplicates-from-sorted-list/ Given a sorted linked list, delete all duplicates such that each element appear only once. Example 1: Input: 1->1->2 Output: 1->2 Example 2: Input: 1->1->2->3->3 Output: 1->…
https://leetcode.com/problems/sqrtx/ Implement int sqrt(int x). Compute and return the square root of x, where x is guaranteed to be a non-negative integer. Since the return type is an integer, the decimal digits are truncated and only the…
https://leetcode.com/problems/add-binary/ Given two binary strings, return their sum (also a binary string). The input strings are both non-empty and contains only characters 1 or 0. Example 1: Input: a = "11", b = "1" Output: "100" Exampl…
https://leetcode.com/problems/plus-one/ Given a non-empty array of digits representing a non-negative integer, plus one to the integer. The digits are stored such that the most significant digit is at the head of the list, and each element…
https://leetcode.com/problems/count-and-say/ The count-and-say sequence is the sequence of integers with the first five terms as following: 1 11 21 1211 111221 1 is read off as "one 1" or 11. 11 is read off as "two 1s" or 21. 21 is read of…
https://leetcode.com/problems/length-of-last-word/ Given a string s consists of upper/lower-case alphabets and empty space characters ' ', return the length of last word in the string. If the last word does not exist, return 0. Note: A wor…
https://leetcode.com/problems/search-insert-position/ Given an integer array nums, find the contiguous subarray (containing at least one number) which has the largest sum and return its sum. Example: Input: [-2,1,-3,4,-1,2,1,-5,4], Output:…
https://leetcode.com/problems/search-insert-position/ Given a sorted array 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 may assume no duplicates i…
https://leetcode.com/problems/implement-strstr/ Implement strStr(). Return the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack. Example 1: Input: haystack = "hello", needle = "ll" Output: 2 Exam…
https://leetcode.com/problems/remove-element/ Given an array nums and a value val, remove all instances of that value in-place and return the new length. Do not allocate extra space for another array, you must do this by modifying the inpu…
https://leetcode.com/problems/remove-duplicates-from-sorted-array/ Given a sorted array nums, remove the duplicates in-place such that each element appear only once and return the new length. Do not allocate extra space for another array, …
https://leetcode.com/problems/merge-two-sorted-lists/ Merge two sorted linked lists and return it as a new list. The new list should be made by splicing together the nodes of the first two lists. Example: Input: 1->2->4, 1->3->4 Output: 1-…
https://leetcode.com/problems/valid-parentheses/ Given a string 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 t…
https://leetcode.com/problems/longest-common-prefix/ 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: ["flower","flow","flight…
https://leetcode.com/problems/roman-to-integer/ 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 その名の通り、ローマ数字を数値に変換するという問題です。 "…
https://leetcode.com/problems/palindrome-number/ Determine whether an integer is a palindrome. An integer is a palindrome when it reads the same backward as forward. Example 1: Input: 121 Output: true Example 2: Input: -121 Output: false E…
この問題はBad評価も多いですが、公式のSolutionと異なる解法が色々Discussionされているという意味で、面白いです。 https://leetcode.com/problems/reverse-integer/ Given a 32-bit signed integer, reverse digits of an integer. Example 1: Input: 123…
19/7/7時点でLeetCodeの第一問目に掲載されている問題ですが、シンプルでいて意外に深みのある良問。 https://leetcode.com/problems/two-sum/ Given an array of integers, return indices of the two numbers such that they add up to a specific target.…
