【链表】2017多校训练三 HDU 6058 Kanade's sum

1 #include<iostream>
2 #include<cstdio>
3 #include<cstring>
4 #include<string>
5 #include<cmath>
6 #include<algorithm>
7 #include<queue>
8 #include<stack>
9 #include<map>
10 using namespace std;
11 const int maxn=5e5+3;
12 typedef long long ll;
13 int a[maxn];
14 int p[maxn];
15 int pre[maxn];
16 int nxt[maxn];
17 int b[maxn];
18 int c[maxn];
19 int n,k;
20 int main()
21 {
22     int T;
23     scanf("%d",&T);
24     while(T--)
25     {
26         scanf("%d%d",&n,&k);
27         for(int i=1;i<=n;i++)
28         {
29             scanf("%d",&a[i]);
30             p[a[i]]=i;
31             pre[i]=i-1;
32             nxt[i]=i+1;
33         }
34         ll ans=0;
35         for(int i=1;i<=n;i++)
36         {
37             ll num=0;
38             int pos=p[i];
39             int cntr=0,cntl=0;
40             for(int j=pos;j<=n&&cntr<k;j=nxt[j])
41             {
42                 b[cntr++]=nxt[j]-j;
43             }
44             for(int j=pos;j>=1&&cntl<k;j=pre[j])
45             {
46                 if(k-1-cntl>=cntr)
47                 {
48                     cntl++;
49                     continue;
50                 }
51                 else
52                 {
53                     c[cntl]=j-pre[j];
54                     num+=b[k-1-cntl]*c[cntl];
55                     cntl++;
56                 }
57
58             }
59             ans+=num*i;
60             nxt[pre[pos]]=nxt[pos];
61             pre[nxt[pos]]=pre[pos];
62         }
63         printf("%lld\n",ans);
64     }
65     return 0;
66  }