poj2299 Ultra-QuickSort

Ultra-QuickSort
Time Limit: 7000MS   Memory Limit: 65536K
Total Submissions: 50361   Accepted: 18458

Description

poj2299 Ultra-QuickSort_第1张图片In this problem, you have to analyze a particular sorting algorithm. The algorithm processes a sequence of n distinct integers by swapping two adjacent sequence elements until the sequence is sorted in ascending order. For the input sequence 
9 1 0 5 4 , 
Ultra-QuickSort produces the output 
0 1 4 5 9 . 
Your task is to determine how many swap operations Ultra-QuickSort needs to perform in order to sort a given input sequence. 

Input

The input contains several test cases. Every test case begins with a line that contains a single integer n < 500,000 -- the length of the input sequence. Each of the the following n lines contains a single integer 0 ≤ a[i] ≤ 999,999,999, the i-th input sequence element. Input is terminated by a sequence of length n = 0. This sequence must not be processed.

Output

For every input sequence, your program prints a single line containing an integer number op, the minimum number of swap operations necessary to sort the given input sequence.

Sample Input

5
9
1
0
5
4
3
1
2
3
0

Sample Output

6
0

Source

Waterloo local 2005.02.05



离散化+树状数组求逆序对

(离散化用map会超时…)




#include<iostream>
#include<cstdio>
#include<cmath>
#include<algorithm>
#include<cstring>
#include<cstdlib>
#include<map>
#define F(i,j,n) for(int i=j;i<=n;i++)
#define D(i,j,n) for(int i=j;i>=n;i--)
#define LL long long
#define MAXN 500005
#define pa pair<int,int>
using namespace std;
int n,b[MAXN],f[MAXN];
LL ans;
struct data
{
	int val,pos;
}a[MAXN];
int read()
{
	int ret=0,flag=1;char ch=getchar();
	while (ch<'0'||ch>'9'){if (ch=='-') flag=-1;ch=getchar();}
	while (ch>='0'&&ch<='9'){ret=ret*10+ch-'0';ch=getchar();}
	return ret*flag;
}
void add(int k)
{
	for(int i=k;i<=n;i+=i&(-i)) f[i]++;
}
LL getsum(int k)
{
	LL ret=0;
	for(int i=k;i>0;i-=i&(-i)) ret+=f[i];
	return ret;
}
bool cmp(data x,data y)
{
	return x.val<y.val;
}
int main()
{
	n=read();
	while (n)
	{
		memset(f,0,sizeof(f));
		ans=0;
		F(i,1,n) a[i].val=read(),a[i].pos=i;
		sort(a+1,a+n+1,cmp);
		F(i,1,n)
		{
			if (i>1&&a[i].val==a[i-1].val) b[a[i].pos]=b[a[i-1].pos];
			else b[a[i].pos]=i;
		}
		D(i,n,1)
		{
			if (b[i]>1) ans+=getsum(b[i]-1);
			add(b[i]);
		}
		printf("%lld\n",ans);
		n=read();
	}
}


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