51nod 1574 排列转换

 1 #include <bits/stdc++.h>
 2 
 3 using namespace std;
 4 
 5 const int maxn = 200000 + 5;
 6 int a[maxn];
 7 int b[maxn];
 8 bool vis[maxn];
 9 
10 int main()
11 {
12     int n;
13     scanf("%d",&n);
14 
15     memset(vis,0,sizeof(vis));
16 
17     for(int i=0;i<n;i++)
18         scanf("%d",&a[i]);
19 
20     for(int i=0;i<n;i++) {
21         int tmp;
22         scanf("%d",&tmp);
23         b[tmp] = i;
24     }
25 
26     for(int i=0;i<n;i++) {
27         a[i] = b[a[i]];
28     }
29 
30     long long ans = 0;
31     for(int i=0;i<n;i++) {
32         if(vis[i])
33             continue;
34         long long sum = 0;
35 
36         for(int j=i;!vis[j];j=a[j]) {
37             sum +=(abs(j-a[j]));
38             vis[j] = 1;
39         }
40         ans +=(sum)/2;
41     }
42 
43     printf("%lld\n",ans);
44 
45     return 0;
46 }