A833.Cow Frisbee--Silver

普及/提高-

USACO

通过率:0%

时间限制:1.00s

内存限制:128MB

题目描述

Farmer John's NN cows (N3×105)N \leq 3 \times 10^5) have heights 1,2,,N1, 2, \ldots, N. One day, the cows are standing in a line in some order playing frisbee;
let h1hNh_1 \ldots h_N denote the heights of the cows in this order (so the
hh's are a permutation of 1N1 \ldots N).
Two cows at positions ii and jj in the line can successfully throw the
frisbee back and forth if and only if every cow between them has height lower
than min(hi,hj)\min(h_i, h_j).
Please compute the sum of distances between all pairs of locations i<ji<j at
which there resides a pair of cows that can successfully throw the frisbee
back and forth. The distance between locations ii and jj is ji+1j-i+1.

输入格式

The first line of input contains a single integer NN. The next line of input
contains h1hNh_1 \ldots h_N, separated by spaces.

输出格式

Output the sum of distances of all pairs of locations at which there are cows
that can throw the frisbee back and forth. Note that the large size of
integers involved in this problem may require the use of 64-bit integer data
types (e.g., a "long long" in C/C++).

输入输出样例

  • 输入#1

    7
    4 3 1 2 5 6 7
    

    输出#1

    24
    

说明/提示

The pairs of successful locations in this example are as follows:
(1, 2), (1, 5), (2, 3), (2, 4), (2, 5), (3, 4), (4, 5), (5, 6), (6, 7)

首页