[ACM]Ultra-QuickSort
Time Limit: 7000MS Memory Limit: 65536KB
Total Submissions: 20 Accepted: 7
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
Hint:
Source:
Waterloo local 2005.02.05
这题没有什么可说的,直接调用系统的排序函数进行排序就行了,代码如下:
#include <iostream> #include <algorithm> using namespace std; #define MAXN 500001 int a[MAXN],t[MAXN],n; __int64 ans; void Merge(int l,int m,int r){ int i=0,j=l,k=m+1; while(j<=m && k<=r){ if(a[j]>a[k]){ t[i++]=a[k++]; ans+=m-j+1; } else t[i++]=a[j++]; } while(j<=m) t[i++]=a[j++]; while(k<=r) t[i++]=a[k++]; for(j=0;j<i;j++){ a[l+j]=t[j]; } } void Mergesort(int l,int r){ if(l<r){ int m=(l+r)/2; Mergesort(l,m); Mergesort(m+1,r); Merge(l,m,r); } } int main(){ int i; while(scanf("%d",&n) && n){ ans=0; for(i=0;i<n;i++) scanf("%d",a+i); Mergesort(0,n-1); printf("%I64d ",ans); } return 0; }
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