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  1. //Lib
  2. #include<cstdio>
  3. #include<cstring>
  4. #include<cstdlib>
  5. #include<cmath>
  6. #include<ctime>
  7.  
  8. #include<iostream>
  9. #include<algorithm>
  10. #include<vector>
  11. #include<string>
  12. #include<queue>
  13. #include<stack>
  14. #include<set>
  15. #include<map>
  16. using namespace std;
  17. //Macro
  18. #define rep(i,a,b)  for(int i=a,tt=b;i<=tt;++i)
  19. #define drep(i,a,b) for(int i=a,tt=b;i>=tt;--i)
  20. #define erep(i,e,x) for(int i=x;i;i=e[i].next)
  21. #define irep(i,x)   for(__typeof(x.begin()) i=x.begin();i!=x.end();i++)
  22. #define brep(i,x)   for(int i=x;i<=limit;i+=lowbit(i))
  23. #define bdrep(i,x)  for(int i=x;i>0;i-=lowbit(i))
  24. #define read()  (strtol(ipos,&ipos,10))
  25. #define sqr(x)  ((x)*(x))
  26. #define pb  push_back
  27. #define PS  system("pause");
  28. typedef long long   ll;
  29. typedef pair<int,int> pii;
  30. const int oo=~0U>>1;
  31. const double inf=1e100;
  32. const double eps=1e-6;
  33. string name="", in=".in", out=".out";
  34. //Var
  35. struct BIT
  36. {
  37.     int s[200008],limit;
  38.     inline int lowbit(int x){return x&-x;}
  39.     void Set(int l){memset(s,0,sizeof s);limit=l;}
  40.     void Update(int x,int delta)
  41.     {
  42.         brep(i,x)s[i]+=delta;
  43.     }
  44.     int Get(int x,int y)
  45.     {
  46.         int ret=0;
  47.         bdrep(i,y)ret+=s[i];
  48.         bdrep(i,x)ret-=s[i];
  49.         return ret;
  50.     }
  51. }T;
  52. int n,num[200008],vis[200008],ans;
  53. void Work()
  54. {
  55.     scanf("%d",&n);
  56.     T.Set(n<<2);
  57.     rep(i,1,n<<1)
  58.         scanf("%d",num+i);
  59.     rep(i,1,n<<1)
  60.     {
  61.         if(!vis[num[i]])
  62.             T.Update(i,1),vis[num[i]]=i;
  63.         else
  64.         {
  65.             ans+=T.Get(vis[num[i]]-1,i)-1;
  66.             T.Update(vis[num[i]],-1);
  67.         }
  68.     }
  69.     cout<<ans<<endl;
  70. }
  71. int main()
  72. {
  73. //  freopen((name+in).c_str(),"r",stdin);
  74. //  freopen((name+out).c_str(),"w",stdout);
  75. //  Init();
  76.     Work();
  77.     return 0;
  78. }
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https://ideone.com/lAs4K
language:
C++ (gcc 8.3)
created:
12 years ago
visibility:
public

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