#include<cstdio>
#include<iostream>
#include<cstring>
#include<cstdlib>
using namespace std;
struct node
{
	int x,y;
}a[500005];
int l[500005],r[500005],n;
int cmp(const void *x1,const void *x2)
{
	node n1=*(node *)x1;
	node n2=*(node *)x2;
	if(n1.x!=n2.x) return n1.x-n2.x;
	else return n1.y-n2.y;
}
int lowbit(int x)
{
	return x & -x;
}
void gaibian(int x)
{
	while (x<=n)
	{
		l[x]+=1;
		x+=lowbit(x);
	}
}
int qiuhe(int x)
{
	int ans=0;
	while(x>0)
	{
		ans+=l[x];
		x-=lowbit(x);
	}
	return ans;
}
int main()
{
	int i; long long ans=0;
	while(scanf("%d",&n)!=EOF)
	{
		if(n==0) break;
		for(i=1;i<=n;i++) 
		{
			scanf("%d",&a[i].x);
			a[i].y=i;
		}
		qsort(a+1,n,sizeof(node),cmp);
		for(i=1;i<=n;i++) r[a[i].y]=i;
		for(i=1;i<=n;i++) l[i]=0;
		for(i=1;i<=n;i++)
		{
			gaibian(r[i]);
			ans+=i-qiuhe(r[i]);
		}
		printf("%I64d\n",ans);
	}
	return 0;
}

• Re:树状数组C++,为什么WA？？ (2) mouae 2017-11-08 18:43:40
• Re:树状数组C++,为什么WA？？ (1119) jugggg 2017-11-26 14:45:31
• Re:树状数组C++,为什么WA？？ (1046) 201601014225 2017-11-28 10:42:10
• Re:树状数组C++,为什么WA？？ (1046) lujianjun16 2017-12-05 07:22:03