157. Read N Characters Given Read4 Total Accepted: 19570 Total Submissions: 66588 Difficulty: Easy Contributors: Admin The API: int read4(char *buf) reads 4 characters at a time from a file. The return value is the actual number of characters read. For example, it returns 3 if there is only 3 characters left in the file. …
Continue reading “Leetcode 157: Read N Characters Given Read4”
301. Remove Invalid Parentheses Total Accepted: 23550 Total Submissions: 69307 Difficulty: Hard Contributors: Admin Remove the minimum number of invalid parentheses in order to make the input string valid. Return all possible results. Note: The input string may contain letters other than the parentheses ( and ). Examples: “()())()” -> [“()()()”, “(())()”] “(a)())()” -> [“(a)()()”, …
314. Binary Tree Vertical Order Traversal Total Accepted: 13025 Total Submissions: 38434 Difficulty: Medium Contributors: Admin Given a binary tree, return the vertical order traversal of its nodes’ values. (ie, from top to bottom, column by column). If two nodes are in the same row and column, the order should be from left to right. …
Continue reading “Leetcode 314: Binary Tree Vertical Order Traversal”
155. Min Stack Total Accepted: 96784 Total Submissions: 383098 Difficulty: Easy Contributors: Admin Design a stack that supports push, pop, top, and retrieving the minimum element in constant time. push(x) — Push element x onto stack. pop() — Removes the element on top of the stack. top() — Get the top element. getMin() — Retrieve …
This is the interview question from http://stackoverflow.com/questions/3492302/easy-interview-question-got-harder-given-numbers-1-100-find-the-missing-numbe?rq=1: You are given a bag of numbers which are 0 ~ N-1 integers except k numbers. Return the k missing numbers. The solution should operate in O(N) time complexity and O(k) space complexity. Although the highest voted post uses some theorem to solve the question, I would like to …
311. Sparse Matrix Multiplication Total Accepted: 13356 Total Submissions: 26970 Difficulty: Medium Contributors: Admin Given two sparse matrices A and B, return the result of AB. You may assume that A‘s column number is equal to B‘s row number. Code from collections import defaultdict class Solution(object): def multiply(self, A, B): “”” :type A: List[List[int]] …
Continue reading “Leetcode 311: Sparse Matrix Multiplication”
237. Delete Node in a Linked List Total Accepted: 114749 Total Submissions: 255293 Difficulty: Easy Contributors: Admin Write a function to delete a node (except the tail) in a singly linked list, given only access to that node. Supposed the linked list is 1 -> 2 -> 3 -> 4 and you are given the …
Continue reading “Leetcode 237: Delete Node in a Linked List”
117. Populating Next Right Pointers in Each Node II Total Accepted: 74952 Total Submissions: 225622 Difficulty: Hard Contributors: Admin Follow up for problem “Populating Next Right Pointers in Each Node“. What if the given tree could be any binary tree? Would your previous solution still work? Note: You may only use constant extra space. For …
Continue reading “Leetcode 117: Populating Next Right Pointers in Each Node II”
371. Sum of Two Integers Total Accepted: 42501 Total Submissions: 82322 Difficulty: Easy Contributors: Admin Calculate the sum of two integers a and b, but you are not allowed to use the operator + and -. Example:Given a = 1 and b = 2, return 3. Code class Solution(object): def getSum(self, a, b): “”” …
292. Nim Game Total Accepted: 105850 Total Submissions: 194593 Difficulty: Easy Contributors: Admin You are playing the following Nim Game with your friend: There is a heap of stones on the table, each time one of you take turns to remove 1 to 3 stones. The one who removes the last stone will be …