优美的排列II 给定两个整数 n 和 k,你需要实现一个数组,这个数组包含从 1 到 n 的 n 个不同整数,同时满足以下条件: ① 如果这个数组是 [a1, a2, a3, ... , an] ,那么数组 [|a1 - a2|, |a2 - a3|, |a3 - a4|, ... , |an-1 - an|] 中应该有且仅有 k 个不同整数:. ② 如果存在多种答案,你只需实现并返回其中任意一种. 示例 1: 输入: n = 3, k = 1 输出: [1, 2, 3] 解释: [1, 2,…

667. 优美的排列 II 给定两个整数 n 和 k,你需要实现一个数组,这个数组包含从 1 到 n 的 n 个不同整数,同时满足以下条件: ① 如果这个数组是 [a1, a2, a3, - , an] ,那么数组 [|a1 - a2|, |a2 - a3|, |a3 - a4|, - , |an-1 - an|] 中应该有且仅有 k 个不同整数:. ② 如果存在多种答案,你只需实现并返回其中任意一种. 示例 1: 输入: n = 3, k = 1 输出: [1, 2, 3] 解释: [1, 2…

Problem Link: http://oj.leetcode.com/problems/path-sum-ii/ The basic idea here is same to that of Path Sum. However, since the problem is asking for all possible root-to-leaf paths, so we should use BFS but not DFS. The python code is as follows. # D…

Problem Link: http://oj.leetcode.com/problems/word-ladder-ii/ Basically, this problem is same to Word Ladder I, which uses a double-direction BFS. However, the difference is that we need to keep track of all paths during the double-direction BFS in o…

Problem Link: http://oj.leetcode.com/problems/palindrome-partitioning-ii/ We solve this problem by using Dynamic Programming. Optimal Sub-structure Assume a string S has the palindrome minimum cuts n, and S = W1 + W2 + ... + Wn where Wi is a palindro…

Problem link: http://oj.leetcode.com/problems/single-number-ii/ The problem seems like the Single Number. Suppose we have following (3m+1) numbers in the array A: x0, x1, x1, x1, ..., xm, xm, xm We are asked to find out the value of x0. However we ca…

Problem link: http://oj.leetcode.com/problems/word-break-ii/ This problem is some extension of the word break problem, so the solution is based on the discussion in Word Break. We also use DP to solve the problem. In this solution, A[i] is not a bool…

http://oj.leetcode.com/problems/pascals-triangle-ii/ 杨辉三角2,比杨辉三角要求的空间上限制Could you optimize your algorithm to use only O(k) extra space?其实计算当前行,也只用到前一行了.再前面的没有用. class Solution { public: vector<int> getRow(int rowIndex) { // IMPORTANT: Please reset a…

Given an integer array of size n, find all elements that appear more than ⌊ n/3 ⌋ times. The algorithm should run in linear time and in O(1) space. Hint: How many majority elements could it possibly have? Do you have a better hint? Suggest it! [题目分析]…

/** * Definition for singly-linked list. * struct ListNode { * int val; * ListNode *next; * ListNode(int x) : val(x), next(NULL) {} * }; */ class Solution { public: ListNode *detectCycle(ListNode *head) { ListNode *p1, *p2; //p1和p2从链表的第一个节点出发,p1每次移动一…