ThinkingLion的专栏

DescriptionYangyang takes part in the ACM Summer Training. She loves AC, but there is so much knowledge to learn, For example, Dynamic Programming, Greedy, Search, Graph, Data Structure, and

题目：DescriptionHuicpc0215 has downloaded a lots of files in his desktop. Since there are too many files in the desktop, he wants to delete some files in the desktop. But some files

题目：DescriptionA convex polygon with n edges can be divided into several triangles by some non-intersect diagonals. We denote d(n) is the number of the different ways to divide th

题目链接：http://acm.hdu.edu.cn/showproblem.php?pid=5147太久没做这种题啦，，而且本来树状数组理解的不好。。结果卡了好久。。- -这道题目教我们求的是一个符合条件的index (a,b,c,d) 要符合a正解是枚举c，求得c之前符合条件的a,b对数x,再求得比c大的个数d为y，那么答案就是x*y；我们先正序求树状数组，用数组f[i]代表出