phil的博客

There are two sorted arrays nums1 and nums2 of size m and n respectively.Find the median of the two sorted arrays. The overall run time complexity should be O(log (m+n)).You may assume nums1 and num...

In an array A containing only 0s and 1s, a K-bit flip consists of choosing a (contiguous) subarray of length K and simultaneously changing every 0 in the subarray to 1, and every 1 in the subarray to ...

Given an array of citations (each citation is a non-negative integer) of a researcher, write a function to compute the researcher’s h-index.According to the definition of h-index on Wikipedia: “A sci...

You are given a string containing only 4 kinds of characters ‘Q’, ‘W’, ‘E’ and ‘R’.A string is said to be balanced if each of its characters appears n/4 times where n is the length of the string.Ret...

拓扑排序的经典应用。将课程看作图中的节点，先修关系看作边，由先修课指向后修课，则问题抽象为一个图的节点的拓扑排序问题。我的这篇博客中介绍了对于无环图如何进行拓扑排序。代码class Solution {public: bool canFinish(int numCourses, vector<pair<int, int>>& pres) { ...

Leetcode 先序，中序，后序遍历的题目链接：144. Binary Tree Preorder Traversal94. Binary Tree Inorder Traversal145. Binary Tree Postorder Traversal1. 简要介绍一下先序，中序，后序遍历的区别：例如下面这棵树：它的遍历结果如下：先序：8 3 1 6 4 7 10 14 13...

Given an array of non-negative integers, you are initially positioned at the first index of the array.Each element in the array represents your maximum jump length at that position.Your goal is to r...

Given s1, s2, s3, find whether s3 is formed by the interleaving of s1 and s2.Example 1:Input: s1 = “aabcc”, s2 = “dbbca”, s3 = “aadbbcbcac”Output: trueExample 2:Input: s1 = “aabcc”, s2 = “dbbc...

Given n pairs of parentheses, write a function to generate all combinations of well-formed parentheses.For example, given n = 3, a solution set is:[“((()))”,“(()())”,“(())()”,“()(())”,“()()()”...

原题链接Given a string S, we can transform every letter individually to be lowercase or uppercase to create another string. Return a list of all possible strings we could create.Examples:Input: S ...