随笔分类 -  leetcode

• leetcode Permutation Sequence
  摘要：题目描述： Example 1: Example 2: 即：对于一个整数n，共有n！个排列，给出数字k，返回第k个全排列 观察题目可得如下规律： 对于n，其中每个字母 开头的全排列共有n-1！个，如数字3，以 1开头的共有2！个。 因此：m= k / (n-1)! 可以确定出第一个数字， 将该数字加 阅读全文
  posted @ 2018-10-16 11:31 miss_UU 阅读(213) 评论(0) 推荐(0)
• leetcode 之 word search
  摘要：题目描述 79. Word Search •Total Accepted: 85823 •Total Submissions: 357336 •Difficulty: Medium Given a 2D board and a word, find if the word exists in the grid. The word can be constructed from let... 阅读全文
  posted @ 2016-08-19 10:42 miss_UU 阅读(181) 评论(0) 推荐(0)
• leetcode 之 Palindrome Partitioning
  摘要：即, 给定一个字符串,计算所有的回文子串. 思路: 采用深度dfs的思想,对应aab, 网上搜到一张 图: 依次遍历字符串, step [0, len), 判断s[step:len] 是否问回文子串, 如果是, step +1 继续判断,代码如下: 阅读全文
  posted @ 2016-08-04 18:04 miss_UU 阅读(213) 评论(0) 推荐(0)
• leetcode 之 Excel Sheet Column Number
  摘要：意思是将一个字符串转成相应的数字,其转换规则是 excel表格计数那样, A->1 AA->27 稍稍分析得知, 其实是一个26进制的问题, 容易得出: AA = 26^1*nums(A) + 26^0*nums(A) ABC= 26^2*nums(A)+26^1*nums(B)+.... 代码如下 阅读全文
  posted @ 2016-08-01 12:43 miss_UU 阅读(166) 评论(0) 推荐(0)
• leetcode 之 Count Numbers with Unique Digits
  摘要：1. 回溯: 输入n的话, 不考虑10^n, 则总共有n位数. 使用 cur[n] 代表当前的数字. 使用一个flag[10] 代表0~9位数字, 每次放入一个数字,则flag对应的数字置为1, 代码如下: 上述回溯法,在时间上超时了T_T 2.动态规划: 根据提示4, f(k) = 9 * 9 * 阅读全文
  posted @ 2016-07-28 15:25 miss_UU 阅读(176) 评论(0) 推荐(0)
• leetcode 之Jump Game
  摘要：题目描述： 即， 给定一组非负数， 每一个数字代表可以向后走的最大步数， 如A= [2, 3, 1, 1, 4], A[0] = 2, 代表从A[0]可以访问到(A[1] = 3, A[2] =1), 同理，类推。 如果从第一个数开始， 按上述方法， 可以访问到最后一个数， 则该数组返回True， 阅读全文
  posted @ 2016-07-27 09:50 miss_UU 阅读(155) 评论(0) 推荐(0)
• leetcode 之 Symmetric Tree
  摘要：# Definition for a binary tree node.# class TreeNode(object):# def __init__(self, x):# self.val = x# self.left = None# self.right = Noneclass Solution 阅读全文
  posted @ 2016-07-26 14:15 miss_UU 阅读(154) 评论(0) 推荐(0)
• leetcode 之 House Robber
  摘要：题目描述： You are a professional robber planning to rob houses along a street. Each house has a certain amount of money stashed, the only constraint stopp 阅读全文
  posted @ 2016-07-26 10:23 miss_UU 阅读(180) 评论(0) 推荐(0)
• leetcode 之 Minimum Path Sum
  摘要：题目描述: Given a m x n grid filled with non-negative numbers, find a path from top left to bottom right which minimizes the sum of all numbers along its 阅读全文
  posted @ 2016-06-21 18:41 miss_UU 阅读(195) 评论(0) 推荐(0)
• leetcode 之 Longest Increasing Subsequence
  摘要：题目描述： Given an unsorted array of integers, find the length of longest increasing subsequence. For example, Given [10, 9, 2, 5, 3, 7, 101, 18], The lon 阅读全文
  posted @ 2016-06-15 14:38 miss_UU 阅读(173) 评论(0) 推荐(0)
• leetcode 之Maximum Product Subarray
  摘要：题目描述: Find the contiguous subarray within an array (containing at least one number) which has the largest product. For example, given the array [2,3,- 阅读全文
  posted @ 2016-06-14 16:57 miss_UU 阅读(169) 评论(0) 推荐(0)
• leetcode 之 Verify Preorder Serialization of a Binary Tree
  摘要：题目描述： One way to serialize a binary tree is to use pre-order traversal. When we encounter a non-null node, we record the node's value. If it is a null 阅读全文
  posted @ 2016-06-06 16:52 miss_UU 阅读(179) 评论(0) 推荐(0)
• leetcode 之 Combinations
  摘要：描述: Given two integers n and k, return all possible combinations of k numbers out of 1 ... n. For example, If n = 4 and k = 2, a solution is: 运行结果: [[ 阅读全文
  posted @ 2016-06-06 10:53 miss_UU 阅读(212) 评论(0) 推荐(0)
• leetcode 之 Kth Smallest Element in a BST
  摘要：题目描述： 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 ≤ 阅读全文
  posted @ 2016-06-02 11:14 miss_UU 阅读(206) 评论(0) 推荐(0)
• leetcode 之 Different Ways to Add Parentheses
  摘要：题目描述： Given a string of numbers and operators, return all possible results from computing all the different possible ways to group numbers and operato 阅读全文
  posted @ 2016-06-02 10:34 miss_UU 阅读(255) 评论(0) 推荐(0)
• leetcode 之Binary Tree Postorder Traversal
  摘要：题目描述： Given a binary tree, return the postorder traversal of its nodes' values. For example: Given binary tree {1,#,2,3}, return [3,2,1]. 即 给定一颗二叉树。 使 阅读全文
  posted @ 2016-05-26 17:47 miss_UU 阅读(160) 评论(0) 推荐(0)
• leetcode 之 Permutation
  摘要：描述： 其实我没有看到这个题 给定一个数n， 求其全排列。 如3 则输出 [1, 2, 3][1, 3, 2][2, 1, 3][2, 3, 1][3, 1, 2][3, 2, 1] 使用回溯法求解。 使用n维数组visit 来标记一个数是否已经加入集合。回溯树如下： 深度优先搜索，当搜索深度为n时 阅读全文
  posted @ 2016-05-25 16:05 miss_UU 阅读(403) 评论(0) 推荐(0)
• leetcode 之 Next Permutation
  摘要：题目描述： Implement next permutation, which rearranges numbers into the lexicographically next greater permutation of numbers. If such arrangement is not 阅读全文
  posted @ 2016-05-25 10:22 miss_UU 阅读(164) 评论(0) 推荐(0)
• leetcode之Unique Binary Search Trees
  摘要：题目描述: Given n, how many structurally unique BST's (binary search trees) that store values 1...n? For example, Given n = 3, there are a total of 5 uniq 阅读全文
  posted @ 2016-05-25 09:12 miss_UU 阅读(169) 评论(0) 推荐(0)
• leetcode 之 Insertion Sort List
  摘要：题目描述: 难度: 中等 Sort a linked list using insertion sort. 中文描述: 使用插入排序对一个链表进行排序. 解析: 插入排序就不多说了,主要看插入排序对于单链表来说怎么做. 在单链表中,由于无法拿到链表的前一个元素,所有每次遍历必须从head 开始.找到 阅读全文
  posted @ 2016-05-11 10:30 miss_UU 阅读(176) 评论(0) 推荐(0)