Given n balloons, indexed from 0 to n-1. Each balloon is painted with a number on it represented by array nums. You are asked to burst all the balloons. If the you burst balloon i you will get nums[left] * nums[i] * nums[right] coins. Here left and right are adjacent indices of i. After the burst, the left and rightthen becomes adjacent.

Find the maximum coins you can collect by bursting the balloons wisely.

Given an array of integers A, find the sum of min(B), where B ranges over every (contiguous) subarray of A.

Since the answer may be large, return the answer modulo 10^9 + 7.

915. Partition Array into Disjoint Intervals

Given two strings s and t which consist of only lowercase letters.

String t is generated by random shuffling string s and then add one more letter at a random position.

Find the letter that was added in t.

滑动窗口系列

linux中用于查看cpu、内存、磁盘IO的命令有vmstat，free等。

此文档总结一些易忘记和易混淆的基础概念。

本文档非原创。主要总结io多路复用中的几个模型。
IO多路复用是指内核一旦发现进程指定的一个或者多个IO条件准备读取，它就通知该进程。

memcpy、memmove，memcpy和strcpy分别用

本文档讲解linux中的5种io模型。并非原创。