Ultra-QuickSort

Time Limit: 7000 MS Memory Limit: 65536 KB

Description

In this problem, you have to analyze a particular sorting algorithm. The algorithm processes a sequence of n distinct integers by swapping twoadjacent sequence elements until the sequence is sorted in ascending order. For the input sequence9 1 0 5 4 ,Ultra-QuickSort produces the output0 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

59105431230

Sample Output

60

Source

Waterloo local 2005.02.05#include<cstdio>#include<iostream>using namespace std;#define max 500002int tp[max];int arr[max],b[max];long long cnt=0;//总逆序数void q(int a[],int start,int mid,int end){int i =start,j=mid+1,k=start;while(i<=mid&&j<=end){if(a[i]<=a[j]){cnt+=j-mid-1;b[k++]=a[i++];}else{cnt+=j-k;b[k++]=a[j++];}}while(i<=mid){cnt+=end-mid;b[k++]=a[i++];}while(j<=end){b[k++]=a[j++];}for(int i=start; i<=end; i++){a[i]=b[i];}}void p(int a[], int start,int end){if(start<end){int mid=(start+end)/2;p(a,start,mid);p(a,mid+1,end);q(a,start,mid,end);}}int main(){int n;while(scanf("%d",&n)!=-1){if(n==0){break;}for(int i=0; i<n; i++){scanf("%d",&arr[i]);}cnt=0;p(arr,0,n-1);printf("%I64d\n",cnt/2);}return 0;}