Description Merge two sorted (ascending) linked lists and return it as a new sorted list. The new sorted list should be made by splicing together the nodes of the two lists and sorted in ascending order. Example Given 1->3->8->11->15->null,…

21. Merge Two Sorted Lists[easy] Merge two sorted linked lists and return it as a new list. The new list should be made by splicing together the nodes of the first two lists. 解法一: /** * Definition for singly-linked list. * struct ListNode { * int val…

Description Given a collection of intervals, merge all overlapping intervals. Example Given intervals => merged intervals: [ [ (1, 3), (1, 6), (2, 6), => (8, 10), (8, 10), (15, 18) (15, 18) ] ] Challenge O(n log n) time and O(1) extra space. 题意:给定一个…

class Solution {public:   ListNode* mergeTwoLists(ListNode* l1, ListNode* l2) {   ListNode *p; ListNode *p1=p;   while(l1!=NULL && l2!=NULL){      if((l1->val)<(l2->val)){           p->next=l1;           p=p->next;           l1=l1-&…

Description Given a sorted (increasing order) array, Convert it to create a binary tree with minimal height. There may exist multiple valid solutions, return any of them. Example Given [1,2,3,4,5,6,7], return 4 / \ 2 6 / \ / \ 1 3 5 7 解题:题目要求根据一个有序的数…

Description Given a non-overlapping interval list which is sorted by start point. Insert a new interval into it, make sure the list is still in order and non-overlapping (merge intervals if necessary). Example Insert (2, 5) into [(1,2), (5,9)], we ge…

Description Write a method to replace all spaces in a string with %20. The string is given in a characters array, you can assume it has enough space for replacement and you are given the true length of the string. You code should also return the new…

Description Sort a linked list using insertion sort. Example Given 1->3->2->0->null, return 0->1->2->3->null. 解题:用插入法排序链表.很简单的一道题目,但还是出现了很多问题. 总结一下遇到的问题: (1)没有头结点的情况下,为了方便可以构造一个,返回头结点的next就行了. (2)没有必要一直在原来的链表上纠结,完全可以申请一个头结点,将原链表结点一…

Description Given an array and a value, remove all occurrences of that value in place and return the new length. The order of elements can be changed, and the elements after the new length don't matter. Example Given an array [0,4,4,0,0,2,4,4], value…

Description 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. Example Given a binary tree as follow: 1 / \ 2 3 / \ 4 5 The minimum depth is …

Description Given two strings, write a method to decide if one is a permutation of the other. Example abcd is a permutation of bcad, but abbe is not a permutation of abe 解题:遇到过类似的题目,比较简单的方法是,把字符串转化为字符数组,然后排序.比较每一位的数是否相等.这样做效率比较低,代码如下: public class So…

Description Given a permutation which contains no repeated number, find its index in all the permutations of these numbers, which are ordered in lexicographical order. The index begins at 1. Example Given [1,2,4], return 1. 解题:至今仍然不理解这个“字典中的顺序”是什么意思,…

Description Determine the number of bits required to flip if you want to convert integer n to integer m. Both n and m are 32-bit integers. Example Given n = 31 (11111), m = 14 (01110), return 2. 解题:比较两个整数对应的二进制数,共有多少位不同.注意,负数也包含在内.“>>>”在无符号右移,用0补…

Description Invert a binary tree. Example 1 1 / \ / \ 2 3 => 3 2 / \ 4 4    解题:题目要求讲二叉树的左子树和右子树对调一下,用递归来做很简单: /** * Definition of TreeNode: * public class TreeNode { * public int val; * public TreeNode left, right; * public TreeNode(int val) { * this…

Description You have two numbers represented by a linked list, where each node contains a single digit. The digits are stored in reverse order, such that the 1's digit is at the head of the list. Write a function that adds the two numbers and returns…

Description Write a method anagram(s,t) to decide if two strings are anagrams or not. Clarification What is Anagram? Two strings are anagram if they can be the same after change the order of characters. Example Given s = "abcd", t = "dcab&q…

Description Implement an algorithm to determine if a string has all unique characters. Example Given "abc", return true. Given "aab", return false. Challenge What if you can not use additional data structures? 解题:题目要求判断字符串是否有重复的元素,并且要求…

Description Using O(1) time to check whether an integer n is a power of 2. Example For n=4, return true; For n=5, return false; Challenge O(1) time 题解:题目要求判断一个数是不是2的幂次方,并且规定时间复杂度为线性级.那么,就不能用常规的循环求解思路去解题了,之前做过一个不用加号求两数之和的题目.这两个题目有点类似,可以通过位运算来快速求解.先考虑这…

Merge two sorted (ascending) linked lists and return it as a new sorted list. The new sorted list should be made by splicing together the nodes of the two lists and sorted in ascending order. Have you met this question in a real interview? Yes Exampl…

Merge k Sorted Lists Merge k sorted linked lists and return it as one sorted list. Analyze and describe its complexity.   采用优先队列priority_queue 把ListNode放入优先队列中,弹出最小指后,如果该ListNode有下一个元素,则把下一个元素放入到队列中     /** * Definition for singly-linked list. * stru…

Merge k Sorted Lists Merge k sorted linked lists and return it as one sorted list. Analyze and describe its complexity. 题目意思: 合并K条已经排序的链表.分析时间复杂度. 解题思路: 很容易就想起之前学的合并两条链表的算法,这一题其实就是那个题目的扩展,变成合并K条了.我采用的方法就是迭代法. 如果只有一条,直接返回.如果只有两条,就只需要调用mergeTwo一下.如果超过两…

描述 Merge k sorted linked lists and return it as one sorted list. Analyze and describe its complexity. Example: Input: [   1->4->5,   1->3->4,   2->6 ] Output: 1->1->2->3->4->4->5->6 思路 借鉴Merge Two Sorted Lists的解决思路,对两个数…

作者: 负雪明烛 id: fuxuemingzhu 个人博客:http://fuxuemingzhu.cn/ 个人公众号:负雪明烛 本文关键词:合并,有序链表,递归,迭代,题解,leetcode, 力扣,Python, C++, Java 目录 题目描述 题目大意 解题方法 迭代 Python解法 C++解法 Java解法 递归 日期 题目地址:https://leetcode.com/problems/merge-two-sorted-lists/ 题目描述 Merge two sorted…

作者: 负雪明烛 id: fuxuemingzhu 个人博客:http://fuxuemingzhu.cn/ 个人公众号:负雪明烛 本文关键词:合并,链表,单链表,题解,leetcode, 力扣,Python, C++, Java 题目地址: https://leetcode.com/problems/merge-k-sorted-lists/description/ 题目描述: Merge k sorted linked lists and return it as one sorted li…

Merge k sorted linked lists and return it as one sorted list. Analyze and describe its complexity. 这道题让我们合并k个有序链表,之前我们做过一道Merge Two Sorted Lists 混合插入有序链表,是混合插入两个有序链表.这道题增加了难度,变成合并k个有序链表了,但是不管合并几个,基本还是要两两合并.那么我们首先考虑的方法是能不能利用之前那道题的解法来解答此题.答案是肯定的,但是需要修改…

Merge two sorted linked lists and return it as a new list. The new list should be made by splicing together the nodes of the first two lists. 这道混合插入有序链表和我之前那篇混合插入有序数组非常的相似Merge Sorted Array,仅仅是数据结构由数组换成了链表而已,代码写起来反而更简洁.具体思想就是新建一个链表,然后比较两个链表中的元素值,把较小的…

问题: Merge k sorted linked lists and return it as one sorted list. Analyze and describe its complexity. 官方难度: Hard 翻译: 合并k个已排序的链表,得到一个新的链表并且返回其第一个节点.分析并阐述其复杂度. 这是No.021(Merge Two Sorted Lists)的深入研究. 可以借鉴归并排序的思想,对于长度为k的数组,依次进行二路归并,返回这两个链表合并之后的头结点(利用No.…

1. Merge Two Sorted Lists 我们先来看这个 问题: Merge two sorted linked lists and return it as a new list. The new list should be made by splicing together the nodes of the first two lists. 是的,这是一个非常简单链表操作问题.也许你只需要花几分种便能轻松写出代码. 2. Merge k Sorted Lists 我们现在来研究这…

Merge k Sorted Lists Merge k sorted linked lists and return it as one sorted list. Analyze and describe its complexity. 两个方法: 方法1. 利用 STL 中的 multiset (根据结点内的值)自动对指针排序.空间 O(N), 时间 O(NlogN). (亦可用于 k 个无序链表).(AC: 164ms) /** * Definition for singly-linked…

Merge Two Sorted Lists https://leetcode.com/problems/merge-two-sorted-lists/ Merge two sorted linked lists and return it as a new list. The new list should be made by splicing together the nodes of the first two lists. 算法思想: 连接两个排好序(假设升序,降序类似)的链表,这是一…