POJ 2299 Ultra-QuickSort
2012-08-26 10:04
357 查看
DescriptionIn 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.InputThe 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.OutputFor 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 0Sample Output
6 0
这个题的意思是问你冒泡排序中交换值的次数,也就是让你求序列中的逆数对之和;
对于这个问题,首先想到的是归并排序求逆数对,在二路归并的时候通过比较左右两边队头的值求得
如归并时:4 5 6 和 1 2 3 ,sum=op[1]+op[2]+op[3]=9;
这个就不多说了;
这个题也可以用树状数组来做:
首先离散化:把输入进去的数用它们所在的下标表示,排序以后它们下标的逆数就代替了它的逆数,这样的好处是使树状数组的下标之间不会差太远,起到一个压缩作用;
其后就是计算了:从数组的最后一个往第一个算,如果它不是最大的,则它到根结点的逆数都要+1;
下面是我用归并按自己理解写的,虽然写的跟挫,但是好懂:
LANGUAGE:C++
CODE:
这个是用数状数组写的,也不比归并快多少,也是NLOGN的算法;#include<iostream>using namespace std;long long cnt;void merge(int array[],int left,int mid,int right){ int* temp=new int[right-left+1]; int i,j,p; for(i=left,j=mid+1,p=0;i<=mid&&j<=right;p++) { if(array[i]<=array[j])temp[p]=array[i++]; else temp[p]=array[j++],cnt+=(mid-i+1); } while(i<=mid)temp[p++]=array[i++]; while(j<=right)temp[p++]=array[j++]; for(i=left,p=0;i<=right;i++)array[i]=temp[p++]; delete temp;}void mergesort(int array[],int left,int right){ if(left==right)array[left]=array[right]; else { int mid=(left+right)/2; mergesort(array,left,mid); mergesort(array,mid+1,right); merge(array,left,mid,right); }}int main(){ int n,array[500005]; while(cin>>n,n) { cnt=0; for(int i=0;i<n;i++) cin>>array[i]; mergesort(array,0,n-1); cout<<cnt<<endl; } return 0;}
LANGUAGE:C++
CODE:
#include<iostream>#include<string.h>#include<algorithm>using namespace std;#define maxn 500001struct node{ int key; int to; bool const operator<(const struct node& a)const { return key<a.key; }} data[maxn];void update(int interval[],int n,int x,int w){ for(int i=x; i<=n; i+=(i&-i)) { interval[i]+=w; }}int getsum(int interval[],int x){ int sum=0; for(int i=x; i>0; i-=(i&-i)) sum+=interval[i]; return sum;}int main(){ int n,interval[maxn]; long long sum; while(cin>>n,n) { for(int i=1; i<=n; i++) { cin>>data[i].key; data[i].to=i; } sum=0; memset(interval,0,sizeof(interval)); sort(data+1,data+n+1); for(int i=n; i>0; i--) { sum+=getsum(interval,data[i].to); update(interval,n,data[i].to,1); } cout<<sum<<endl; }}
相关文章推荐
- POJ 2299 Ultra-QuickSort(求逆序对)
- poj 2299 Ultra-QuickSort :归并排序求逆序数
- poj 2299 Ultra-QuickSort(归并排序)||(树状数组+离散化)
- poj 2299 Ultra-QuickSort【树状数组】
- POJ 2299 Ultra-QuickSort (树状数组)
- POJ 2299 Ultra-QuickSort
- POJ 2299 Ultra-QuickSort
- POJ 2299 Ultra-QuickSort(归排并序)
- poj-2299-Ultra-QuickSort(线段树 || 归并排序)
- POJ[2299]Ultra-QuickSort 逆序对:线段树||树状数组||分治
- POJ-2299 Ultra-QuickSort 逆序对数量
- POJ2299 Ultra-QuickSort(归并排序)
- POJ 2299 Ultra-QuickSort (排序+数据离散化+求顺序数)
- poj 2299 Ultra-QuickSort(求逆序对)&& poj 1804
- POJ 2299 Ultra-QuickSort【树状数组 ,逆序数】
- poj 2299 Ultra-QuickSort(树状数组+离散化的题目)据说是简单题,不过还是觉得好难。。。
- POJ-2299-Ultra-QuickSort
- POJ 2299 Ultra-QuickSort(树状数组+离散化)
- Hdu 1394 Minimum Inversion Number、Poj 2299 Ultra-QuickSort
- poj2299 Ultra-QuickSort (树状数组+离散化)