单调栈的尝试

Bad Hair Day
Time Limit: 2000MS
Memory Limit: 65536K
Total Submissions: 14989
Accepted: 4977
 


Description


Some of Farmer John's N cows (1 ≤ N ≤ 80,000) are having a bad hair day! Since each cow is self-conscious about her messy hairstyle, FJ wants to count the number of other cows that can see the top of other cows' heads.


Each cow i has a specified height hi (1 ≤ hi ≤ 1,000,000,000) and is standing in a line of cows all facing east (to the right in our diagrams). Therefore, cow i can see the tops of the heads of cows in front of her (namely cows i+1, i+2, and so on), for as long as these cows are strictly shorter than cow i.


Consider this example:


            =
=          =
=    -      =         Cows facing right -->
=    =     =
= -  = = =
= = = = = =
1 2 3 4 5 6 
Cow#1 can see the hairstyle of cows #2, 3, 4
Cow#2 can see no cow's hairstyle
Cow#3 can see the hairstyle of cow #4
Cow#4 can see no cow's hairstyle
Cow#5 can see the hairstyle of cow 6
Cow#6 can see no cows at all!


Let ci denote the number of cows whose hairstyle is visible from cow i; please compute the sum of c1 through cN.For this example, the desired is answer 3 + 0 + 1 + 0 + 1 + 0 = 5.


Input


Line 1: The number of cows, N.
Lines 2..N+1: Line i+1 contains a single integer that is the height of cow i.
Output


Line 1: A single integer that is the sum of c1 through cN.
Sample Input


6
10
3
7
4
12
2
Sample Output


5

初次做这道题的时候用了很普通的搜索，结果会超时，然后上网找题解的时候看到了单调栈在这道题中的使用

单调栈代码实现：

点击打开链接http://www.cnblogs.com/dongsheng/archive/2012/08/02/2619638.html

遍历方法实现（似乎是用了剪枝，在暴搜的基础上节约了时间，未检验正误）：

点击打开链接http://blog.csdn.net/qq_38538733/article/details/74935846

下面是有关单调栈的一些介绍：

点击打开链接http://blog.csdn.net/liujian20150808/article/details/50752861

点击打开链接http://www.cnblogs.com/szy-wlxy/p/4622662.html