大意: 给定$n$元素序列$a$, 依次插入二叉搜索树, 求出$dfs$序列, 对序列每个元素模$2$得到一个长为$2n-1$的$01$序列$s1$. 再给定$01$序列$s2$, 求$s2$在$s1$中的出现次数. 二叉搜索树的一个节点$x$, 右儿子是满足$a[y]>a[x],y>x$的最小$y$, 左儿子是满足$a[y]<a[x],y>x$的最小$y$. 所以按照$a$排序后, 编号的笛卡尔树就是二叉搜索树.…

转自——http://blog.csdn.net/qwe20060514/article/details/8112550 =============================以下是最小生成树+并查集======================================[HDU]1213   How Many Tables   基础并查集★1272   小希的迷宫   基础并查集★1325&&poj1308  Is It A Tree?   基础并查集★1856   More i…

poj2549 Sumsets 题目链接: http://poj.org/problem?id=2549 题意:给你一个含有n(n<=1000)个数的数列,问这个数列中是否存在四个不同的数a,b,c,d,使a+b+c=d;若存在则输出最大的d 思路:完全暴力的话O(n^4),会T,可以考虑双向搜索,公式变形为a+b=d-c:分别枚举a+b和c-d,将值和下标存在结构体中,再二分查找即可 #include<cstdio> #include<iostream> #include&…

Halloween treats Time Limit: 2000MS   Memory Limit: 65536K Total Submissions: 7644   Accepted: 2798   Special Judge Description Every year there is the same problem at Halloween: Each neighbour is only willing to give a certain total number of sweets…

Find a multiple Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 7192   Accepted: 3138   Special Judge Description The input contains N natural (i.e. positive integer) numbers ( N <= 10000 ). Each of that numbers is not greater than 15000…

The Pilots Brothers' refrigerator Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 22286   Accepted: 8603   Special Judge Description The game “The Pilots Brothers: following the stripy elephant” has a quest where a player needs to open a…

Flip Game Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 37427   Accepted: 16288 Description Flip game is played on a rectangular 4x4 field with two-sided pieces placed on each of its 16 squares. One side of each piece is white and the…

Corn Fields Time Limit: 2000MS   Memory Limit: 65536K Total Submissions: 9806   Accepted: 5185 Description Farmer John has purchased a lush new rectangular pasture composed of M by N (1 ≤ M ≤ 12; 1 ≤ N ≤ 12) square parcels. He wants to grow some yumm…

Sum of Consecutive Prime Numbers Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 20050   Accepted: 10989 Description Some positive integers can be represented by a sum of one or more consecutive prime numbers. How many such representatio…

Tree Recovery Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 11939   Accepted: 7493 Description Little Valentine liked playing with binary trees very much. Her favorite game was constructing randomly looking binary trees with capital le…