PAT研究生入学考试2015.03第三题Insertion or Heap Sort (25) 题解

#include <iostream>
#include <stdio.h>
//1ms 288kb
const int MAX=110;

int a[MAX];
int b[MAX];
int c[MAX];
int n;
bool finished=false;

bool check(const int(&a)[MAX])
{
bool same=true;
for (int i=0;i<n;i++)
if (a[i]!=b[i])
{
same=false;
break;
}
return same;
}

void adjust_down(int a[MAX],int i,int last)
{
int child=2*i+1;
int temp=a[i];
while (child<=last)
{
if (child<last && a[child]<a[child+1]) child++;
if (temp>=a[child]) break;
a[(child-1)/2]=a[child];
child=child*2+1;
}
a[(child-1)/2]=temp;
}

void Swap(int& a,int& b)
{
int temp=a;
a=b;
b=temp;
}

void heap_sort(int (&a)[MAX])
{
finished=false;
for (int i=(n-2)/2;i>=0;i--)
adjust_down(a,i,n-1); //this step isn't included in the 'iteration' of the question

for (int i=n-1;i>0;i--)
{
Swap(a[i],a[0]);
adjust_down(a,0,i-1);
if (finished) return;
finished=check(a);
}
}

void insertion_sort(int (&a)[MAX])
{
finished=false;
for (int i=1;i<n;i++)
{
int temp=a[i];
int j;
for (j=i;j>0;j--)
if (a[i]>=a[j-1]) break;
for (int k=i;k>j;k--)
a[k]=a[k-1];
a[j]=temp;
if (finished) return;
finished=check(a);
}
}

int main()
{
scanf("%d",&n);
for (int i=0;i<n;i++)
{
scanf("%d",&a[i]);
c[i]=a[i];
}
for (int i=0;i<n;i++)
scanf("%d",&b[i]);

heap_sort(a);
if (finished)
{
printf("Heap Sort\n");
for (int i=0;i<n-1;i++)
printf("%d ",a[i]);
printf("%d",a[n-1]);
}
else
{
insertion_sort(c);
printf("Insertion Sort\n");
for (int i=0;i<n-1;i++)
printf("%d ",c[i]);
printf("%d",c[n-1]);
}
return 0;
}