计算满足i<j<k且a[i]>a[j]>a[k]的三元组数目 树状数组 Codeforces 61E 敌人很弱

http://codeforces.com/problemset/problem/61/E

E. Enemy is weak

time limit per test

5 seconds

memory limit per test

256 megabytes

input

standard input

output

standard output

The Romans have been attacking again. This time, the Romans are significantly superior, however, Shapur is prepared to defeat them. It is said that a lion will not fear a hundred sheep.

Nonetheless, Shapur must identify their vulnerabilities in order to vanquish them. Consequently, he assigns each army an identifier as a marker for its vulnerabilities.

He perceives that an army's deficiency corresponds to the