P2866 [USACO06NOV]糟糕的一天Bad Hair Day

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  • 题目提供者 FarmerJohn2
  • 评测方式 云端评测
  • 标签 模拟 USACO 2006
  • 难度 普及/提高-
  • 时空限制 1000ms / 128MB

题解

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    题意翻译

    农夫约翰有$N (N \leq 80000)$头奶牛正在过乱头发节。每一头牛都站在同一排面朝东方,而且每一头牛的身高为$h_i$。第$N$头牛在最前面,而第$1$头牛在最后面。 对于第$i$头牛前面的第$j$头牛,如果$h_i>h_{i+1}$并且$h_i>h_{i+2}$ $\cdots$ $h_i>h_j$,那么认为第$i$头牛可以看到第$i+1$到第$j$头牛

    定义$C_i$为第$i$头牛所能看到的别的牛的头发的数量。请帮助农夫约翰求出$\sum_{i=1}^n C_i$

    题目描述

    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.

    输入输出格式

    输入格式:

    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.

    输出格式:

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

    输入输出样例

    输入样例#1: 复制
    6
    10
    3
    7
    4
    12
    2
    输出样例#1: 复制
    5
    提示
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