Question

我想对大输入实施计数排序以比较时间复杂度。我写了以下代码。它适用于小输入（int size = 50; size＆lt; = 500; size = size + 100）但是当我增加大小时（int size = 10000; size＆lt; = 100000; size = size + 50000）i无法得到正确的输出。需要帮助谢谢你。

 #include <iostream>
#include<ctime>
#include<cstdlib>
#include<iomanip>
 using namespace std;
void counting_sort(int a[], int size)
{
int i, j, k;
int idx = 0;
int low, high;

low = high = a[0];
for(i = 1; i < size; i++) 
    {
 low = (a[i] < low) ? a[i] : low;
 high = (a[i] > high) ? a[i] : high;
}

k = high - low + 1;
int *c = new int [k]; 
for(i = 0; i < k; i++) c[i] = 0;
for(i = 0; i < size; i++) c[a[i] - low]++;
for(i = low; i <= high; i++) 
    for(j = 0; j < c[i - low]; j++) a[idx++] = i;
          for (int i = 0; i < size;  i++ )
          { 
       cout << a[i] << " ";
          } delete [] c;
  }

   int main()
     {
          srand(time(0));
          int*a;
          double t1, t2;
          for(int size = 50; size<=500; size= size+100)
          {
             a= new int[size];
              for(int i=0;i<size;i++)
             {
              a[i]=rand()%10000;
             }
            t1=clock();
           counting_sort(a, size-1);
           t2=clock();
           cout << setw(10) << (t2 - t1) / CLK_TCK << "sec\n" << endl;
           delete[]a;
         }

}

Answer 1

Ideone问题。 Visual Studio工作正常。此外，counting_sort(a, size)，而非size-1

计数排序不适用于大型数据集

1 个答案: