OJ-Problems-Source/HDOJ/4911_autoAC.cpp
2016-09-10 11:34:41 +08:00

49 lines
1.1 KiB
C++

#include<stdio.h>
#include<string.h>
#define N 100005
__int64 cnt, k;
int a[N],c[N];
void merge(int a[], int first, int mid, int last, int c[])
{
int i = first, j = mid + 1;
int m = mid, n = last;
int k = 0;
while(i <= m || j <= n)
{
if(j > n || (i <= m && a[i] <= a[j]))
c[k++] = a[i++];
else
{
c[k++] = a[j++];
cnt += (m - i + 1);
}
}
for(i = 0; i < k; i++)
a[first + i] = c[i];
}
void merge_sort(int a[], int first, int last, int c[])
{
if(first < last)
{
int mid = (first + last) / 2;
merge_sort(a, first, mid, c);
merge_sort(a, mid+1, last, c);
merge(a, first, mid, last, c);
}
}
int main()
{
int n;
while(~scanf("%d%I64d",&n,&k))
{
memset(c, 0, sizeof(c));
cnt = 0;
for(int i = 0; i < n; i++)
scanf("%d", &a[i]);
merge_sort(a, 0, n-1, c);
if(k >= cnt) cnt = 0;
else cnt -= k;
printf("%I64d\n",cnt);
}
}