UVALive 6508 Permutation Graphs

 1 #include<stdio.h>
 2 #include<string.h>
 3 
 4 int temp[100005],a[100005],b[100005],c[100005],b1[100005];
 5 long long num;
 6 
 7 void merg_sort(int a[],int l,int r)
 8 {
 9     int  i,j,len=r-l,p1,p2;
10     if(len<=1)
11         return;
12     int mid=l+len/2;
13     merg_sort(a,l,mid);
14     merg_sort(a,mid,r);
15     p1=l,p2=mid;
16     for(i=l;i<r;i++)
17     {
18         if(p1==mid)
19         {
20             temp[i]=a[p2];
21             p2++;
22         }
23         else if(p2==r)
24         {
25             temp[i]=a[p1];
26             p1++;
27         }
28         else
29         {
30             if(a[p1]<=a[p2])
31             {
32                 temp[i]=a[p1];
33                 p1++;
34             }
35             else
36             {
37                 temp[i]=a[p2];
38                 p2++;
39                 num=num+mid-p1;
40             }
41         }
42     }
43     for(i=l;i<r;i++)
44         a[i]=temp[i];
45     return;
46 }
47 
48 int main()
49 {
50     int T;
51     int n,i,j,k;
52     scanf("%d",&T);
53     while(T--)
54     {
55         num=0;
56         scanf("%d",&n);
57         for(i=1;i<=n;i++)
58             scanf("%d",&b[i]);
59         for(i=1;i<=n;i++)
60             b1[b[i]]=i;
61 
62         for(i=1;i<=n;i++)
63             scanf("%d",&c[i]);
64         for(i=1;i<=n;i++)
65             a[i]=b1[c[i]];
66 
67         /*for(i=1;i<=n;i++)
68             printf("%d ",a[i]);*/
69         merg_sort(a,1,n+1);
70         printf("%lld\n",num);
71     }
72     return 0;
73 }