Given a binary tree, return the postorder traversal of its nodes' values. Example: Input: [1,null,2,3] 1 \ 2 / 3 Output: [3,2,1] Follow up: Recursive solution is trivial, could you do it iteratively? Solution: 使用两个栈,来实现: 使用一个栈来实现 class Solution { pub…
#include "000库函数.h" //使用折半算法 牛逼算法 class Solution { public: double myPow(double x, int n) { if (n == 0)return 1; double res = 1.0; for (int i = n; i != 0; i /= 2) { if (i % 2 != 0) res *= x; x *= x; } return n > 0 ? res : 1 / res; } }; //同样使用二…
Sort a linked list using insertion sort. A graphical example of insertion sort. The partial sorted list (black) initially contains only the first element in the list.With each iteration one element (red) is removed from the input data and inserted in…
Given a singly linked list L: L0→L1→…→Ln-1→Ln,reorder it to: L0→Ln→L1→Ln-1→L2→Ln-2→… You may not modify the values in the list's nodes, only nodes itself may be changed. Example 1: Given 1->2->3->4, reorder it to 1->4->2->3. Example 2: G…
Given a binary tree, return the preorder traversal of its nodes' values. Example: Input: [1,null,2,3] 1 \ 2 / 3 Output: [1,2,3] Follow up: Recursive solution is trivial, could you do it iteratively? Solution: 很简单,使用栈,先存入右节点,再存入左节点,这样就是先弹出左节点了 class S…
Sort a linked list in O(n log n) time using constant space complexity. Example 1: Input: 4->2->1->3 Output: 1->2->3->4 Example 2: Input: -1->5->3->4->0 Output: -1->0->3->4->5 Solution: 复杂度为O(nlogn)有快速排序,并归排序,堆排序,对…
Given n points on a 2D plane, find the maximum number of points that lie on the same straight line. Example 1: Input: [[1,1],[2,2],[3,3]] Output: 3 Explanation: ^ | | o | o | o +-------------> 0 1 2 3 4 Example 2: Input: [[1,1],[3,2]…
Evaluate the value of an arithmetic expression in Reverse Polish Notation. Valid operators are +, -, *, /. Each operand may be an integer or another expression. Note: Division between two integers should truncate toward zero. The given RPN expressi…
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. Note: A leaf is a node with no children. Example: Given binary tree [3,9,20,null,null,15…
本题是力扣网第50题. 实现 pow(x, n) ,即计算 x 的 n 次幂函数. 采用递归和非递归思路python实现. class Solution: #递归思路 def myPow_recursion(self,x,n): if n == 0: #递归终止条件,n==0返回1 return 1 if n < 0: #n小于0,就返回其倒数,-n和其递归结构一致 return 1 / self.myPow_recursion(x,-n) if n & 1: #判断是奇数,则结果为x*(x…
Given a non-empty string s and a dictionary wordDict containing a list of non-empty words, determine if s can be segmented into a space-separated sequence of one or more dictionary words. Note: The same word in the dictionary may be reused multiple t…
Given a reference of a node in a connected undirected graph, return a deep copy (clone) of the graph. Each node in the graph contains a val (int) and a list (List[Node]) of its neighbors. Example: Input: {"$id":"1","neighbors"…
Given a non-empty array of integers, every element appears twice except for one. Find that single one. Note: Your algorithm should have a linear runtime complexity. Could you implement it without using extra memory? Example 1: Input: [2,2,1] Output:…
Given a non-empty array of integers, every element appears three times except for one, which appears exactly once. Find that single one. Note: Your algorithm should have a linear runtime complexity. Could you implement it without using extra memory?…
A linked list is given such that each node contains an additional random pointer which could point to any node in the list or null. Return a deep copy of the list. Example 1: Input: {"$id":"1","next":{"$id":"2&…
