随笔分类 - LeetCode
摘要：Given a non-empty 2D array grid of 0's and 1's, an island is a group of 1's (representing land) connected 4-directionally (horizontal or vertical.) Yo
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摘要：Given a positive integer, check whether it has alternating bits: namely, if two adjacent bits will always have different values. Example 1: Input: 5 O
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摘要：Given a non-empty list of words, return the k most frequent elements. Your answer should be sorted by frequency from highest to lowest. If two words h
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摘要：Given a sorted array consisting of only integers where every element appears twice except for one element which appears once. Find this single element
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摘要：You are given coins of different denominations and a total amount of money. Write a function to compute the number of combinations that make up that a
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摘要：There are 1000 buckets, one and only one of them contains poison, the rest are filled with water. They all look the same. If a pig drinks that poison
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摘要：You are given a circular array nums of positive and negative integers. If a number k at an index is positive, then move forward k steps. Conversely, i
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摘要：A gene string can be represented by an 8-character long string, with choices from "A", "C", "G", "T". Suppose we need to investigate about a mutation
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摘要：Given an integer n, return the largest palindromic integer that can be represented as the product of two n-digits integers. Since the answer can be ve
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摘要：You are given a data structure of employee information, which includes the employee's unique id, his importance value and his direct subordinates' id.
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摘要：On an NxN chessboard, a knight starts at the r-th row and c-th column and attempts to make exactly K moves. The rows and columns are 0 indexed, so the
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摘要：Given a binary tree, find the length of the longest path where each node in the path has the same value. This path may or may not pass through the roo
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摘要：Given two strings A and B, find the minimum number of times A has to be repeated such that B is a substring of it. If no such solution, return -1. For
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摘要：In this problem, a tree is an undirected graph that is connected and has no cycles. The given input is a graph that started as a tree with N nodes (wi
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摘要：You're now a baseball game point recorder. Given a list of strings, each string can be one of the 4 following types: Each round's operation is permane
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摘要：Given a time represented in the format "HH:MM", form the next closest time by reusing the current digits. There is no limit on how many times a digit
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摘要：Given a non-empty string s, you may delete at most one character. Judge whether you can make it a palindrome. Example 1: Example 2: Note: 这道题是之前那道Vali
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摘要：Given a string containing only three types of characters: '(', ')' and '*', write a function to check whether this string is valid. We define the vali
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摘要：Implement a MapSum class with insert, and sum methods. For the method insert, you'll be given a pair of (string, integer). The string represents the k
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摘要：Implement a magic directory with buildDict, and search methods. For the method buildDict, you'll be given a list of non-repetitive words to build a di
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