Description

 

Input

Output

 

Sample Input

3 1 2 2 1

Sample Output

1

 

Data Constraint

分析

简单的树状数组求逆序对，答案等于逆序对数-k，注意当k大于逆序对数输出零

 

#include 
      
       #include 
       
        #include 
        
         #include 
         
          #define lowbit(x) x&-xusing namespace std;typedef long long ll;const int N=1e5+10;ll t[N],a[N],b[N],k;int n,cnt;void Add(int x) {    for (int i=x;i