Ultra-QuickSort
Time Limit: 7000MS | Memory Limit: 65536K | |
Total Submissions: 57710 | Accepted: 21327 |
Description
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
求交换的次数,归并排序
#include<iostream>
using namespace std;
const int N = 500050;
long long int ans;
void merge(int a[],int l,int mid,int r)
{
for(int i = l;i < r;i++)
{
cout << a[i] << " ";
}
cout << endl;
cout << mid << endl;
int temp[N];
int i,j,p = 0;
i = l,j = mid+1;
while(i <= mid && j <= r)
{
if(a[i] <= a[j])
{
temp[p++] = a[i++];
}
else
{
temp[p++] = a[j++];
ans = ans +(mid - i + 1);
}
}
while(i <= mid) temp[p++] = a[i++];
while(j <= r) temp[p++] = a[j++];
for(int i = l,p = 0;i <= r;i++)
{
a[i] = temp[p++];
}
}
void mergesort(int a[],int l,int r)
{
if(l == r) a[r] = a[r];
else
{
int mid = (l + r)/2;
mergesort(a,l,mid);
mergesort(a,mid+1,r);
merge(a,l,mid,r);
}
}
int main()
{
int n,a[N];
while(cin >> n,n)
{
ans = 0;
for(int i = 0;i < n;i++)
{
cin >> a[i];
}
mergesort(a,0,n-1);
cout << ans << endl;
}
return 0;
}