Sort it
Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 3498 Accepted Submission(s): 2536
Problem Description
You want to processe a sequence of n distinct integers by swapping two adjacent sequence elements until the sequence is sorted in ascending order. Then how many times it need.
For example, 1 2 3 5 4, we only need one operation : swap 5 and 4.
Input
The input consists of a number of test cases. Each case consists of two lines: the first line contains a positive integer n (n <= 1000); the next line contains a permutation of the n integers from 1 to n.
Output
For each case, output the minimum times need to sort it in ascending order on a single line.
Sample Input
3
1 2 3
4
4 3 2 1
Sample Output
0 6
#include<stdio.h>
#include<string.h>
#include<algorithm>
using namespace std;
int a[1010];
int b[1010];
int n,cnt;
void merge(int a[],int s,int m,int e)
{
int i=s,j=m+1,k=s;
while(i<=m&&j<=e)
{
if(a[i]<=a[j])
b[k++]=a[i++];
else
{
cnt+=j-k;
b[k++]=a[j++];
}
}
while(i<=m)
b[k++]=a[i++];
while(j<=e)
b[k++]=a[j++];
for(i=s;i<=e;i++)
a[i]=b[i];
}
void mergesort(int a[],int s,int e)
{
if(s<e)
{
int m=(s+e)/2;
mergesort(a,s,m);
mergesort(a,m+1,e);
merge(a,s,m,e);
}
}
int main()
{
int i,j,mm;
while(scanf("%d",&n)!=EOF)
{
for(i=1;i<=n;i++)
scanf("%d",&a[i]);
cnt=0;
mergesort(a,1,n);
printf("%d\n",cnt);
}
return 0;
}
