sorting | Heap Sort

Start with a C + + code to see the process of push sequencing:

1#include <iostream>2#include <algorithm>3 using namespacestd;4 5 BOOLcmpConst intLhsConst intRHS)6 {7     returnLHS >RHS;8 }9 Ten intMain () One { A     intArr[] = {4,2,Ten,9,5,6,8,6,7,1,3}; -Make_heap (arr, arr+Ten); -      for(inti = One; I >=0; --i) { thePop_heap (arr, arr+i); -          for(inti =0; I < One; ++i) cout << Arr[i] <<' '; -cout <<Endl; -     } +  -     return 0; +}

Mainly Make_heap, pop_heap

Make_heap: Build heap, default Max heap-"Get increment array (because POP_HEAP is to take the heap top out and then put it back)

Pop_heap:arr[0] and Arr[i] exchange, and maintain the heap structure of arr[0] to arr[i-1].

Meke_heap can be subdivided into a heap from the bottom to the top, the recursive is to maintain I, you have to maintain the i.left and i.right.

And Pop_heap is the N-Times maintenance root node.

So, in fact, just write a maxheapify.

1 voidMaxheapify (intArr[],intNinti)2 {3     intL =2*i;4     intR =2*i +1;5     intlargest = i;6     if(L < n && Arr[l] >Arr[largest])7largest =L9     if(R < n && Arr[r] >Arr[largest])Tenlargest =R; One  A     if(Largest = = i)return; - swap (Arr[i], arr[largest]); - maxheapify (arr, n, largest); the}

The process of maintaining the heap is simply to keep sinking.

The back of the Meke_heap and pop_heap is not difficult to write.

Makeheap (arr, n):

For i = N/2 Downto 1:

Maxheap (arr, n, i);

Popheap (arr, n):

Swap (arr[0], arr[--n]);

Maxheap (arr, n, 0);

Then the sortHeap is easy to write:

SortHeap (arr, n):

Makeheap (arr, n);

For i = n Downto 0:

Popheap (arr, i);

sorting | Heap Sort