實驗8排序算法實驗比較
背景
排序是計算機內經常進行的一種操作,其目的是將一組“無序”的記錄序列調整爲“有序”的記錄序列。
假設含n個記錄的序列爲{ R1, R2, …, Rn }
其相應的關鍵字序列爲 { K1, K2, …,Kn }
這些關鍵字相互之間可以進行比較,即在它們之間存在着這樣一個關係 :
Kp1≤Kp2≤…≤Kpn
按此固有關係將上式記錄序列重新排列爲{ Rp1, Rp2, …,Rpn }的操作稱作排序。
排序算法是計算機科學中最重要的研究問題之一。對於排序的研究既有理論上的重要意義,又有實際應用價值。它在計算機圖形、計算機輔助設計、機器人、模式識別、及統計學等領域具有廣泛應用。 常見的排序算法有起泡排序、直接插入排序、簡單選擇排序、快速排序、堆排序等。
例1:有時候應用程序本身就需要對信息進行排序。爲了準備客戶賬目,銀行需要根據支票的號碼對支票排序;
例2:在一個繪製互相重疊的圖形對象的程序中,可能需要根據一個“在上方”關係將各對象排序,以便自下而上地繪出對象。
例3:在一個由n個數構成的集合上,求集合中第i小/大的數。
例4:對一個含有n個元數的集合,求解中位數、k分位數。
實驗目的
基於教材內容,任選兩種排序算法,實現並比較性能。
基本要求
(1)至少要有一種排序算法的性能優於O(n2)
(2)對實現的排序算法進行實驗比較,實驗比較數據參見教材7.8章節
(3)排序算法要基於教材,測試輸入的整數數據文件(5個,文件中數據規模分別是100,1K,10K,100K和1M),排序結果也要輸出到文件中。
(4)要在屏幕上輸出排序過程所花費時間
代碼實現
#include<iostream>
#include<fstream>
#include<windows.h>
using namespace std;
LARGE_INTEGER frequency;
int A[1000001],temp[1000001];
int count=0;
void Init(ifstream &infile)
{
int a;
while(!infile.eof())
{
infile>>a;
A[count]=a;
count++;
}
}
void print(ofstream &outfile)
{
for(int i=0;i<count;i++)
{
outfile<<A[i]<<' ';
}
}
int partition(int A[],int l,int r,int p)
{
do
{
while(A[++l]<p);
while(l<r&&A[--r]>p);
swap(A[l],A[r]);
}
while(l<r);
return l;
}
void qsort(int A[],int i,int j)
{
if(j<=i)
return;
int p=(i+j)/2;
swap(A[p],A[j]);
int k=partition(A,i-1,j,A[j]);
swap(A[k],A[j]);
qsort(A,i,k-1);
qsort(A,k+1,j);
}
bool cmp(int x,int y)
{
return x<y;
}
void mergesort(int A[],int temp[],int left,int right)
{
if(left==right)
return;
int mid=(left+right)/2;
mergesort(A,temp,left,mid);
mergesort(A,temp,mid+1,right);
for(int i=left;i<=right;i++)
temp[i]=A[i];
int i1=left;
int i2=mid+1;
for(int curr=left;curr<=right;curr++)
{
if(i1==mid+1)
A[curr]=temp[i2++];
else if(i2>right)
A[curr]=temp[i1++];
else if(cmp(temp[i1],temp[i2]))
A[curr]=temp[i1++];
else
A[curr]=temp[i2++];
}
}
int main()
{
ifstream test_100("100.txt");
ifstream test_1K("1K.txt");
ifstream test_10K("10K.txt");
ifstream test_100K("100K.txt");
ifstream test_1M("1M.txt");
ofstream output_100("output_100.txt");
ofstream output_1K("output_1K.txt");
ofstream output_10K("output_10K.txt");
ofstream output_100K("output_100K.txt");
ofstream output_1M("output_1M.txt");
double dff,begin,end,dfm,dft;
Init(test_100);
QueryPerformanceFrequency(&frequency);//獲得時鐘頻率
dff=(double)frequency.QuadPart;
QueryPerformanceCounter(&frequency);//獲得初始值
begin=frequency.QuadPart;
qsort(A,0,100);
QueryPerformanceCounter(&frequency);//獲得終止值
end=frequency.QuadPart;
dfm=(double)(end-begin);
dft=dfm/dff;
print(output_100);
cout<< "快速排序100:"<<dft*1000<<"ms"<<endl;
QueryPerformanceFrequency(&frequency);//獲得時鐘頻率
dff=(double)frequency.QuadPart;
QueryPerformanceCounter(&frequency);//獲得初始值
begin=frequency.QuadPart;
mergesort(A,temp,0,100);
QueryPerformanceCounter(&frequency);//獲得終止值
end=frequency.QuadPart;
dfm=(double)(end-begin);
dft=dfm/dff;
cout<<"歸併排序100:"<<dft*1000<<"ms"<<endl;
Init(test_1K);
QueryPerformanceFrequency(&frequency);//獲得時鐘頻率
dff=(double)frequency.QuadPart;
QueryPerformanceCounter(&frequency);//獲得初始值
begin=frequency.QuadPart;
qsort(A,0,1000);
QueryPerformanceCounter(&frequency);//獲得終止值
end=frequency.QuadPart;
dfm=(double)(end-begin);
dft=dfm/dff;
print(output_1K);
cout<<"快速排序1K:"<<dft*1000<<"ms"<<endl;
QueryPerformanceFrequency(&frequency);//獲得時鐘頻率
dff=(double)frequency.QuadPart;
QueryPerformanceCounter(&frequency);//獲得初始值
begin=frequency.QuadPart;
mergesort(A,temp,0,1000);
QueryPerformanceCounter(&frequency);//獲得終止值
end=frequency.QuadPart;
dfm=(double)(end-begin);
dft=dfm/dff;
cout<<"歸併排序1K:"<<dft*1000<<"ms"<<endl;
Init(test_10K);
QueryPerformanceFrequency(&frequency);//獲得時鐘頻率
dff=(double)frequency.QuadPart;
QueryPerformanceCounter(&frequency);//獲得初始值
begin=frequency.QuadPart;
qsort(A,0,10000);
QueryPerformanceCounter(&frequency);//獲得終止值
end=frequency.QuadPart;
dfm=(double)(end-begin);
dft=dfm/dff;
print(output_10K);
cout<<"快速排序10K:"<<dft*1000<<"ms"<<endl;
QueryPerformanceFrequency(&frequency);//獲得時鐘頻率
dff=(double)frequency.QuadPart;
QueryPerformanceCounter(&frequency);//獲得初始值
begin=frequency.QuadPart;
mergesort(A,temp,0,10000);
QueryPerformanceCounter(&frequency);//獲得終止值
end=frequency.QuadPart;
dfm=(double)(end-begin);
dft=dfm/dff;
cout<<"歸併排序10K:"<<dft*1000<<"ms"<<endl;
Init(test_100K);
QueryPerformanceFrequency(&frequency);//獲得時鐘頻率
dff=(double)frequency.QuadPart;
QueryPerformanceCounter(&frequency);//獲得初始值
begin=frequency.QuadPart;
qsort(A,0,100000);
QueryPerformanceCounter(&frequency);//獲得終止值
end=frequency.QuadPart;
dfm=(double)(end-begin);
dft=dfm/dff;
print(output_100K);
cout<<"快速排序100K:"<<dft*1000<<"ms"<<endl;
QueryPerformanceFrequency(&frequency);//獲得時鐘頻率
dff=(double)frequency.QuadPart;
QueryPerformanceCounter(&frequency);//獲得初始值
begin=frequency.QuadPart;
mergesort(A,temp,0,100000);
QueryPerformanceCounter(&frequency);//獲得終止值
end=frequency.QuadPart;
dfm=(double)(end-begin);
dft=dfm/dff;
cout<<"歸併排序100K:"<<dft*1000<<"ms"<<endl;
Init(test_1M);
QueryPerformanceFrequency(&frequency);//獲得時鐘頻率
dff=(double)frequency.QuadPart;
QueryPerformanceCounter(&frequency);//獲得初始值
begin=frequency.QuadPart;
qsort(A,0,1000000);
QueryPerformanceCounter(&frequency);//獲得終止值
end=frequency.QuadPart;
dfm=(double)(end-begin);
dft=dfm/dff;
print(output_1M);
cout<<"快速排序1M:"<<dft*1000<<"ms"<<endl;
QueryPerformanceFrequency(&frequency);//獲得時鐘頻率
dff=(double)frequency.QuadPart;
QueryPerformanceCounter(&frequency);//獲得初始值
begin=frequency.QuadPart;
mergesort(A,temp,0,1000000);
QueryPerformanceCounter(&frequency);//獲得終止值
end=frequency.QuadPart;
dfm=(double)(end-begin);
dft=dfm/dff;
cout<<"歸併排序1M:"<<dft*1000<<"ms"<<endl;
return 0;
}
完整代碼及輸入輸出樣例:https://github.com/Prince9821/Data-stucture