Given a roman numeral, convert it to an integer. The answer is guaranteed to be within the range from 1 to 3999. Have you met this question in a real interview? Yes Clarification What is Roman Numeral? https://en.wikipedia.org/wiki/Roman_numerals htt…
Roman to Integer Given a roman numeral, convert it to an integer. Input is guaranteed to be within the range from 1 to 3999. public class Solution { public int romanToInt(String s) { if (s == null || s.length()==0) { return 0; } Map<Character, Intege…
61. Search for a Range[medium] Given a sorted array of n integers, find the starting and ending position of a given target value. If the target is not found in the array, return [-1, -1]. Have you met this question in a real interview? Yes Example Gi…
62. Search in Rotated Sorted Array[medium] Suppose a sorted array is rotated at some pivot unknown to you beforehand. (i.e., 0 1 2 4 5 6 7 might become 4 5 6 7 0 1 2). You are given a target value to search. If found in the array return its index, ot…
74. First Bad Version [medium] The code base version is an integer start from 1 to n. One day, someone committed a bad version in the code case, so it caused this version and the following versions are all failed in the unit tests. Find the first bad…
75. Find Peak Element [medium] There is an integer array which has the following features: The numbers in adjacent positions are different. A[0] < A[1] && A[A.length - 2] > A[A.length - 1]. We define a position P is a peek if: A[P] > A[P-…
2. Add Two Numbers[medium] You are given two non-empty linked lists representing two non-negative integers. The digits are stored in reverse order and each of their nodes contain a single digit. Add the two numbers and return it as a linked list. You…
92. Reverse Linked List II[Medium] Reverse a linked list from position m to n. Do it in-place and in one-pass. For example:Given 1->2->3->4->5->NULL, m = 2 and n = 4, return 1->4->3->2->5->NULL. Note:Given m, n satisfy the fo…
82. Remove Duplicates from Sorted List II[Medium] Given a sorted linked list, delete all nodes that have duplicate numbers, leaving only distinct numbers from the original list. For example,Given 1->2->3->3->4->4->5, return 1->2->5…
159. Find Minimum in Rotated Sorted Array [medium] Suppose a sorted array is rotated at some pivot unknown to you beforehand. (i.e., 0 1 2 4 5 6 7 might become 4 5 6 7 0 1 2). Find the minimum element. Notice You may assume no duplicate exists in the…
There are a total of n courses you have to take, labeled from 0 to n - 1. Some courses may have prerequisites, for example to take course 0 you have to first take course 1, which is expressed as a pair: [0,1] Given the total number of courses and a l…
Given a binary tree, flatten it to a linked list in-place. For example, given the following tree: 1 / \ 2 5 / \ \ 3 4 6 The flattened tree should look like: 1 \ 2 \ 3 \ 4 \ 5 \ 6 Accepted 218,918 Submissions 533,947 [解析]由上图可知,如果右子树不为空,则右子树最后肯定为左子树最有一…
Say you have an array for which the ith element is the price of a given stock on day i. If you were only permitted to complete at most one transaction (ie, buy one and sell one share of the stock), design an algorithm to find the maximum profit. Ex…
Given an array S of n integers, are there elements a, b, c in S such that a + b + c = 0? Find all unique triplets in the array which gives the sum of zero. Notice Elements in a triplet (a,b,c) must be in non-descending order. (ie, a ≤ b ≤ c) The solu…
Implement a stack with min() function, which will return the smallest number in the stack. It should support push, pop and min operation all in O(1) cost. Notice min operation will never be called if there is no number in the stack. Example push(1)…
The gray code is a binary numeral system where two successive values differ in only one bit. Given a non-negative integer n representing the total number of bits in the code, print the sequence of gray code. A gray code sequence must begin with 0. Fo…
Write an efficient algorithm that searches for a value in an m x n matrix. This matrix has the following properties: Integers in each row are sorted from left to right. The first integer of each row is greater than the last integer of the previous ro…
You are given two non-empty linked lists representing two non-negative integers. The most significant digit comes first and each of their nodes contain a single digit. Add the two numbers and return it as a linked list. You may assume the two numbers…
Find the kth largest element in an unsorted array. Note that it is the kth largest element in the sorted order, not the kth distinct element. Example 1: Input: [3,2,1,5,6,4] and k = 2 Output: 5 Example 2: Input: [3,2,3,1,2,4,5,5,6] and k = 4 Output:…
Given an array of integers that is already sorted in ascending order, find two numbers such that they add up to a specific target number. The function twoSum should return indices of the two numbers such that they add up to the target, where index1 m…
Count the number of k's between 0 and n. k can be 0 - 9. Example if n = 12, k = 1 in [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12] we have FIVE 1's (1, 10, 11, 12) 解法一: class Solution { public: // param k : description of k // param n : description of…
You have two numbers represented by a linked list, where each node contains a single digit. The digits are stored in forward order, such that the 1's digit is at the head of the list. Write a function that adds the two numbers and returns the sum as…
Given an integer array, find the top k largest numbers in it. Example Given [3,10,1000,-99,4,100] and k = 3. Return [1000, 100, 10]. 解法一: class Solution { public: /* * @param nums: an integer array * @param k: An integer * @return: the top k larges…
Reverse digits of an integer. Returns 0 when the reversed integer overflows (signed 32-bit integer). Example Given x = 123, return 321 Given x = -123, return -321 解法一: class Solution { public: /* * @param n: the integer to be reversed * @return: th…
Say you have an array for which the ith element is the price of a given stock on day i. Design an algorithm to find the maximum profit. You may complete as many transactions as you like (ie, buy one and sell one share of the stock multiple times). Ho…
Given a string s, partition s such that every substring of the partition is a palindrome. Return all possible palindrome partitioning of s. For example, given s = "aab", Return [ ["aa","b"], ["a","a","…
A message containing letters from A-Z is being encoded to numbers using the following mapping: 'A' -> 1 'B' -> 2 ... 'Z' -> 26 Given an encoded message containing digits, determine the total number of ways to decode it. For example,Given encoded…
Given a 2D board and a word, find if the word exists in the grid. The word can be constructed from letters of sequentially adjacent cell, where "adjacent" cells are those horizontally or vertically neighboring. The same letter cell may not be us…
Given a m x n matrix, if an element is 0, set its entire row and column to 0. Do it in place. 解题思路: 题目乍一看很简单,将矩阵当前为0的位的行列都置为0: 问题在于:当遇到一个已知0时,不能立刻将其行列置0,因为这样会把原本不是0的位更改,导致继续遍历的时候无法区分哪些是初始0,哪些是后改0: 有一个解决方法,就是先遍历所有位,记录所有初始为0的行列坐标,遍历一遍之后,再统一做更改: 但是这个解决方…
