| Time Limit: 7000MS | Memory Limit: 65536K | |
| Total Submissions: 43446 | Accepted: 15822 |
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 Input
Output
Sample Input
5 9 1 0 5 4 3 1 2 3 0
Sample Output
6 0
#include<iostream>
#include<stdio.h>
#define M 500010
int a[M];
int aux[M];
long long int ans;
using namespace std;
void merge(int a[],int l,int mid,int h)
{
for(int k=l;k<=h;++k)
aux[k]=a[k];
int i=l;
int j=mid+1;
for(int k=l;k<=h;++k)
{
if(i>mid)a[k]=aux[j++];
else if(j>h)a[k]=aux[i++];
else if(aux[i]<aux[j])a[k]=aux[i++];
else {
a[k]=aux[j++];
ans+=mid-i+1;//左边的元素比右边的大，那么左边剩下的没比完的元素和这个右边的元素都构成了逆序对！
}
}
}
void sort(int a[],int l,int h)
{
if(l>=h)return ;
int mid=l+(h-l)/2;
sort(a,l,mid);
sort(a,mid+1,h);
merge(a,l,mid,h);
}
int main(int argc, char *argv[])
{
//freopen("2299.in","r",stdin);
int n;
while(scanf("%d",&n)&&n!=0){
ans=0;
for(int i=0;i<n;++i)
scanf("%d",&a[i]);
sort(a,0,n-1);
printf("%lld\n",ans);
}
return 0;
}
POJ 2299 Ultra-QuickSort （归并排序）
原文：http://blog.csdn.net/wdkirchhoff/article/details/41812795