Question

假设有一个由数字1,2,4,3,5,6,7组成的数组我想用heapsort打印1,3,5,7,2,4,6。我一直试图修改基本的heapsort但是没有能够正确输出。

你能帮忙吗？

#include<bits/stdc++.h>
using namespace std;

int heapsize;

int make_left(int i)
{
    return 2*i;
}
int make_right(int i)
{
    return (2*i)+1;
}
void max_heapify(int a[],int i)
{
  //  cout<<heapsize<<endl;
    int largest=i;
   // printf("current position of largest is %d and  largest is %d\n",largest,a[largest]);


    int l=make_left(i);
    int r=make_right(i);
 //   printf("current position of left is %d and  left element is %d\n",l,a[l]);
   // printf("current position of right is %d and  right element is %d\n",r,a[r]);

    if(a[l]>=a[largest] && l<=heapsize && a[l]%2!=0)
        largest=l;
    if(a[r]>a[largest] && r<=heapsize && a[l]%2!=0)
        largest=r;
    //printf("Finalcurrent position of largest is %d and  largest is %d\n",largest,a[largest]);

    if(largest!=i)
    {
        swap(a[i],a[largest]);
        max_heapify(a,largest);
    }
}
void buildmax(int a[],int n)
{
 for (int i=n/2;i>=1;i--)
    {
     //   printf("main theke call\n");
        max_heapify(a,i);
    }
}
void heapsort(int a[],int n)
{
    buildmax(a,n);
//    printf("After being buildmax\n");
  //  for (int i=1;i<=n;i++)
    //{
        //printf("i is %d\n",i);
      //  cout<<a[i]<<endl;

    //}
    for (int i=n;i>=2;i--)
    {
      //   printf("1st element is %d and last elemenet is %d\n",a[1],a[heapsize]);

        swap(a[1],a[heapsize]);
        //printf("1st element is %d and last elemenet is %d\n",a[1],a[heapsize]);
        heapsize--;
        max_heapify(a,1);
    }

}


int main()
{

    int n;
    cin>>n;
    heapsize=n;

    int a[n];
    printf("The elements are\n");
    for (int i=1;i<=n;i++)
    {
        cin>>a[i];
    }
    heapsort(a,n);

    printf("After being sorted\n");
    for (int i=1;i<=n;i++)
    {
        //printf("i is %d\n",i);
        cout<<a[i]<<endl;
    }
}

Answer 1

你可以像以前一样使用相同的heapsort算法，只需用新函数替换小于运算符（或者比你用它进行比较时更大）：

bool LessThan(int a, int b)
{
  if (a%2 == 1 && b%2 == 0)
     return true;
  if (a%2 == 0 && b%2 == 1)
     return false;
  return a < b;
}

如何首先打印奇数的顺序，然后使用heapsort来代替较小的数字？

1 个答案: