(4329)Ping pong

 1 #include<stdio.h>
 2 #include<algorithm>
 3 #include<iostream>
 4 #include<string.h>
 5 #include<queue>
 6 #include<stack>
 7 #include<math.h>
 8 using namespace std;
 9 typedef long long LL;
10 int bitl[200005];
11 int bitr[200005];
12 int lowbit(int x);
13 void addl(int x);
14 void addr(int x);
15 int  askl(int x);
16 int askr(int x);
17 int ans[100005];
18 int bns[100005];
19 int aksl[200005];
20 int aksr[200005];
21 int main(void)
22 {
23         int T;
24         scanf("%d",&T);
25         while(T--)
26         {
27                 int n;
28                 scanf("%d",&n);
29                 memset(bitl,0,sizeof(bitl));
30                 memset(bitr,0,sizeof(bitr));
31                 int i,j;
32                 for(i = 1; i <= n; i++)
33                 {
34                         scanf("%d",&ans[i]);
35                 }
36                 int cn = 1;
37                 for(i = n; i >= 1; i--)
38                 {
39                         bns[cn++] = ans[i];
40                 }
41                 for(i = 1; i <= n; i++)
42                 {
43                     aksl[i] = askl(ans[i]-1);
44                     addl(ans[i]);
45                     aksr[i] = askr(bns[i]-1);
46                     addr(bns[i]);
47                 }
48                 LL sum = 0;
49                 for(i = 2;i <= n-1;i++)
50                 {
51                     sum = sum + (LL)aksl[i]*(LL)(n-i-aksr[n-i+1])+(LL)(i - 1 - aksl[i])*(LL)aksr[n-i+1];
52                 }
53                 printf("%lld\n",sum);
54         }
55         return 0;
56 }
57 int lowbit(int x)
58 {
59         return x&(-x);
60 }
61 void addl(int x)
62 {
63         while(x <= 100000)
64         {
65                 bitl[x]++;
66                 x += lowbit(x);
67         }
68 }
69 void addr(int x)
70 {
71         while(x <= 100000)
72         {
73                 bitr[x]++;
74                 x += lowbit(x);
75         }
76 }
77 int  askl(int x)
78 {
79         int sum = 0;
80         while(x > 0)
81         {
82                 sum += bitl[x];
83                 x -= lowbit(x);
84         }
85         return sum;
86 }
87 int askr(int x)
88 {
89         int sum = 0;
90         while(x > 0)
91         {
92                 sum += bitr[x];
93                 x -= lowbit(x);
94         }
95         return sum;
96 }