小滋

题目描述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.IDEA求树的最小深度：1.递归 先序遍历 （深度优先）

题目描述There are N children standing in a line. Each child is assigned a rating value.You are giving candies to these children subjected to the following requirements:Each child must have at least

题目描述Given an array of integers, every element appears three times except for one. Find that single one.Note:Your algorithm should have a linear runtime complexity. Could you implement it witho

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 usi

题目描述A linked list is given such that each node contains an additional random pointer which could point to any node in the list or null.Return a deep copy of the list.IDEA实现带随机指针链表的深拷贝。深拷贝要就开辟新

题目描述Given a string s and a dictionary of words dict, add spaces in s to construct a sentence where each word is a valid dictionary word.Return all such possible sentences.For example, givens =

题目描述Given a string s and a dictionary of words dict, determine if s can be segmented into a space-separated sequence of one or more dictionary words.For example, givens ="leetcode",dict =["l

题目描述Given a linked list, determine if it has a cycle in it.Follow up:Can you solve it without using extra space?IDEA借助缓慢指针能相遇，说明有环CODE/** * Definition for singly-linked list. * struc

题目描述Given a linked list, return the node where the cycle begins. If there is no cycle, returnnull.Follow up:Can you solve it without using extra space?IDEA借用别人的一个图来说明。设置两个指针，slow每次走一步，

题目描述Given a singly linked list L: L0→L1→…→Ln-1→Ln,reorder it to: L0→Ln→L1→Ln-1→L2→Ln-2→…You must do this in-place without altering the nodes' values.For example,Given{1,2,3,4}, reorder it to

题目描述Given a binary tree, return the preorder traversal of its nodes' values.For example:Given binary tree{1,#,2,3},   1    \     2    /   3return[1,2,3].Note: Recursive solution is

题目描述Given a binary tree, return the postorder traversal of its nodes' values.For example:Given binary tree{1,#,2,3},   1    \     2    /   3return[3,2,1].Note: Recursive soluti

题目描述Sort a linked list using insertion sort.IDEA插入排序：将一个节点插入有序的链表。需要创立新的节点插入node=new ListNode(p->val);pre->next=node;CODE/** * Definition for singly-linked list. * struct ListNode {

题目描述Sort a linked list in O(n log n) time using constant space complexity.IDEA要求空间复杂度为常数，时间复杂度O(nlogn)归并排序：空间复杂度O(n)，时间复杂度O(nlogn)1.首先找到list的中点，用连个指针，一个慢，一个快，慢的每次走一个node，快的每次走两个node，当快的走到lis

题目描述Given n points on a 2D plane, find the maximum number of points that lie on the same straight line.IDEA求出在一条直线上的最大点数。直线的可能情况：1.在一条垂直x轴的直线上（斜率无穷大），2.斜率相同CODE/** * Definition for a poin

题目描述Evaluate the value of an arithmetic expression in Reverse Polish Notation.Valid operators are+,-,*,/. Each operand may be an integer or another expression.Some examples:  ["2", "1", "+",

题目描述请设计一个算法，给一个字符串进行二进制编码，使得编码后字符串的长度最短。IDEA考查的是哈夫曼编码。统计每个字符出现的频率，使得出现频率最小的字符编码长度最长，出现频率最大的字符，编码长度最小。设置一个小顶堆，用于每次取出对顶的最小的两个元素，两这两个元素相加再放入堆中，直到堆中只剩下一个元素位置。编码的长度即为此哈夫曼树非叶子节点数值和，即累加每次从堆中取出的最小两个