poj 2299 树状数组离散化逆序数 水

#include<iostream>
#include<cstring>
#include<algorithm>
#include<cstdio>
#include<vector>
#include<sstream>
#include<string>
#include<climits>
#include<stack>
#include<set>
#include<bitset>
#include<cmath>
#include<deque>
#include<map>
#include<queue>
#define iinf 2000000000
#define linf 1000000000000000000LL
#define dinf 1e200
#define eps 1e-5
#define all(v) (v).begin(),(v).end()
#define sz(x)  x.size()
#define pb push_back
#define mp make_pair
#define lng long long
#define sqr(a) ((a)*(a))
#define pii pair<int,int>
#define pll pair<lng,lng>
#define pss pair<string,string>
#define pdd pair<double,double>
#define X first
#define Y second
#define pi 3.14159265359
#define ff(i,xi,n) for(int i=xi;i<=(int)(n);++i)
#define ffd(i,xi,n) for(int i=xi;i>=(int)(n);--i)
#define ffl(i,r) for(int i=head[r];i!=-1;i=edge[i].next)
#define cc(i,j) memset(i,j,sizeof(i))
#define two(x)			((lng)1<<(x))
#define N 500000
#define M 1000000
#define lson l , mid , rt << 1
#define rson mid + 1 , r , rt << 1 | 1
#define Mod  n
#define Pmod(x) (x%Mod+Mod)%Mod
using namespace std;
typedef vector<int>  vi;
typedef vector<string>  vs;
typedef unsigned int uint;
typedef unsigned lng ulng;
template<class T> inline void checkmax(T &x,T y){if(x<y) x=y;}
template<class T> inline void checkmin(T &x,T y){if(x>y) x=y;}
template<class T> inline T Min(T x,T y){return (x>y?y:x);}
template<class T> inline T Max(T x,T y){return (x<y?y:x);}
template<class T> T gcd(T a,T  b){return (a%b)==0?b:gcd(b,a%b);}
template<class T> T lcm(T a,T b){return a*b/gcd(a,b);}
template<class T> T Abs(T a){return a>0?a:(-a);}
template<class T> inline T lowbit(T n){return (n^(n-1))&n;}
template<class T> inline int countbit(T n){return (n==0)?0:(1+countbit(n&(n-1)));}
template<class T> inline bool isPrimeNumber(T n)
{if(n<=1)return false;for (T i=2;i*i<=n;i++) if (n%i==0) return false;return true;}
struct pp
{
int id,val;
}a
;
int n,newval
,sum
;
inline void update(int x,int add)
{
while(x<=n)
{
sum[x]+=add;
x+=lowbit(x);
}
}
inline int get(int x)
{
int val=0;
while(x)
val+=sum[x],x-=lowbit(x);
return val;
}
bool cmp(pp p,pp q)
{
return p.val<q.val;
}
int main()
{
while(scanf("%d",&n)==1)
{
if(n==0) break;
ff(i,1,n)
{
int t;
scanf("%d",&t);
a[i].id=i,a[i].val=t;
}
sort(a+1,a+1+n,cmp);
int INDEX=0;
a[0].val=iinf;
ff(i,1,n)
if(a[i].val!=a[i-1].val)
newval[a[i].id]=++INDEX;
else
newval[a[i].id]=newval[a[i-1].id];
cc(sum,0);
lng  res=0;
ffd(i,n,1)
res+=get(newval[i]-1),update(newval[i],1);
printf("%I64d\n",res);
}
return 0;
}