문제 링크입니다: https://www.acmicpc.net/problem/10090 10090번: Counting Inversions A permutation of integers from 1 to n is a sequence a1, a2, ..., an, such that each integer from 1 to n is appeared in the sequence exactly once. Two integers in а permutation form an inversion, when the bigger one is before the smaller one. As an example www.acmicpc.net 얼핏 보기에는 시간복잡도 O(N^2)으로 쉽게 풀 수 있는 문제처럼 보이지만 N이 무려 1..
