java_student09的专栏

题目描述Given an input string, reverse the string word by word.For example,Given s = "the sky is blue",return "blue is sky the".

题目描述 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).

题目描述(Permutation Sequence) The set [1,2,3,…,n] contains a total of n! unique permutations. By listing and labeling all of the permutations in order, We get the following sequence (ie, for n =

public class LRUCache { private Map map = null; private int capacity; private int size; public LRUCache(int capacity) { this.capacity = capacity; size = 0; map = new LinkedHashM

题目描述 Given a binary tree and a sum, find all root-to-leaf paths where each path’s sum equals the given sum. For example: Given the below binary tree and sum = 22, 5 / \

题目描述 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. For example: Given the below binary t

题目描述 Given an array of integers, every element appears twice except for one. Find that single one. Note: Your algorithm should have a linear runtime complexity. Could you implement it without

题目描述 Given two words (start and end), and a dictionary, find all shortest transformation sequence(s) from start to end, such that: Only one letter can be changed at a time

题目描述 Given two words (beginWord and endWord), and a dictionary, find the length of shortest transformation sequence from beginWord to endWord, such that: Only one letter can be changed at a time

题目描述 Given a binary tree, determine if it is a valid binary search tree (BST).

/* * Max Points on a Line * */ public int maxPoints(Point[] points) { int max = 0; for(int i=0;i<points.length-1;i++) { for(int j=i+1;j<points.length;j++)

/* * Evaluate Reverse Polish Notation * */ public int evalRPN(String[] tokens) { int result = 0; Stack mStack = new Stack<>(); for(String mString:tokens) {

/* * Sort a linked list using insertion sort. * */ public ListNode insertionSortList(ListNode head) { ListNode p = new ListNode(0); ListNode phead = p; while(head!=null)

/* * Sort a linked list in O(n log n) time using constant space complexity. * */ public ListNode sortList(ListNode head) { ListNode start1 = null; ListNode result = null; ListNode start3 =

题目描述 Given a binary tree, return the level order traversal of its nodes’ values. (ie, from left to right, level by level). For example: Given binary tree {3,9,20,#,#,15,7}, 3 / \ 9