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.
Credits:
Special thanks to @fujiaozhu for adding this problem and creating all test cases.
第一次在leetcode上看到反对票比赞成票多这么多的题目。
C实现代码如下：
int getSum(int a,......
Given a Binary Search Tree (BST), convert it to a Greater Tree such that every key of the original BST is changed to the original key plus sum of all keys greater than the original key in BST.
Input: The root of a Binary Search Tree like this:
5
/ \
2 13
Output: The root of a Greater Tree ......
Given a binary search tree, write a function kthSmallest to find the kth smallest element in it.
Note:
You may assume k is always valid, 1 ≤ k ≤ BST's total elements.
Example 1:
Input: root = [3,1,4,null,2], k = 1
Output: 1
Example 2:
Input: root = [5,3,6,2,4,null,null,1], k ......
Given a binary tree, return the preorder traversal of its nodes' values.
Input: [1,null,2,3]
1
\
2
/
3
Output: [1,2,3]
Follow up: Recursive solution is trivial, could you do it iteratively?
递归实现/**
* Definition for a binary tree node.
* struct TreeNode {
* int val;
* struct Tree......
Given a binary tree, return the inorder traversal of its nodes' values.
Example:
Input: [1,null,2,3]
1
\
2
/
3
Output: [1,3,2]
Output:
Follow up: Recursive solution is trivial, could you do it iteratively?
通过这道leetcode中的题目我们将学习，二叉树（中序 后序 前序）遍历递归与非递归实现，算法采用C编写，在非递归算法中如果采用C++中的栈来实现，将会非常......
Write a function to find the longest common prefix string amongst an array of strings.
If there is no common prefix, return an empty string "".
Example 1:
Input: ["flower","flow","flight"]
Output: "fl"
Example 2:
Input: ["dog&q......
Write a function that takes a string as input and reverse only the vowels of a string.
Example 1:
Given s = "hello", return "holle".
Example 2:
Given s = "leetcode", return "leotcede".
Note:
The vowels does not include the letter "y".
......
Given a singly linked list, determine if it is a palindrome.
Follow up:
Could you do it in O(n) time and O(1) space?
题目描述比较简单：判断链表中的val组成的数字是否是回文数即形如12321 123321即是回文数。
如果题目中没有O(1) space的要求的话，那么可以把链表的值顺序读出放在数组中，然后进行判断。
一种比较巧妙的思路是：逆序(reverse)后半段，然后比较前后两段的值是否相同。
实现代码：
/**
* Definition for......
Given a string containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid.
An input string is valid if:
Open brackets must be closed by the same type of brackets.
Open brackets must be closed in the ......
Write a program to find the node at which the intersection of two singly linked lists begins.
For example, the following two linked lists:
A: a1 → a2
↘
c1 → c2 → c3
↗
B: b1 → b2 → b3
begin to intersect at node c1.
Notes:
If the two linked lists have no interse......