Hduacm—5497

 1 #include <cstring>
 2 #include <cstdio>
 3 #include <iostream>
 4
 5 using namespace std;
 6
 7 typedef long long LL;
 8 const int maxn = 1e5+100;
 9 int a[maxn];
10 struct Bittree
11 {
12     int tr[maxn];
13     void init()
14     {
15         memset(tr,0,sizeof(tr));
16     }
17     void update(int x,int v)
18     {
19         for (;x<maxn;x+=(x&-x)) tr[x] += v;
20     }
21     int query(int x)
22     {
23         int res = 0;
24         for (;x;x-=(x&-x)) res += tr[x];
25         return res;
26     }
27 }L,R;
28
29
30 void slove()
31 {
32     int i,n,m;
33     LL cur = 0,ans;
34     L.init();R.init();
35     scanf("%d%d",&n,&m);
36     for (i = 0;i<n;i++)
37     scanf("%d",&a[i]);
38     for (int i = n-1;i>=m;--i)
39     {
40         cur += R.query(a[i]-1);
41         R.update(a[i],1);
42     }
43     ans = cur;
44
45     for (i = 0;i+m<n;++i)
46     {
47         R.update(a[i+m],-1);
48         cur+=R.query(a[i]-1);
49         cur-=R.query(a[i+m]-1);
50         cur+=L.query(n+1-(a[i]+1));
51         cur-=L.query(n+1-(a[i+m]+1));
52         L.update(n+1-(a[i]),1);
53         ans = min(ans,cur);
54     }
55     printf("%I64d\n",ans);
56 }
57
58 int main()
59 {
60     int T;
61     scanf("%d",&T);
62     while (T--)
63     {
64         slove();
65     }
66     return 0;
67 }

代码