题目下载链接算法可以发现是求逆序对时间复杂度限制在\(O(n\logn)\)树状数组记录每一个值的多少转化为求前缀和#include<iostream>#include<cstdio>#include<algorithm>usingnamespacestd;inttree[500010],ranks[500010],n;longlongans;structpoint{