【算法学习】排序算法-堆排序

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思想：

对全部元素n-1建立大顶堆后，将顶与最后一个元素交换；

而后对n-2个元素建堆，将顶与倒数第二个元素交换；

直到最后两个元素建堆。

C代码

#include "stdio.h"void array_printf(int a[],int n);void sort_heap(int a[],int n);void build_heap(int a[],int e);int main(){int i,a[] = {5,4,3,2,10,9,17,4,2,19,11};int n = sizeof(a)/sizeof(int);sort_heap(a,n);array_printf(a,n);return 0;}void array_printf(int a[],int n){int i ;for (i = 0; i < n; ++i){printf("%d ",a[i]);}printf("\n");}void sort_heap(int a[],int n){int i,x ;for(i=n-1;i>0;i--){build_heap(a,i);x=a[0];a[0] = a[i];a[i] =x;}}void build_heap(int a[],int e){int r,i;int x;for(i=e;i>=1;i--){r=(i-1)/2;if(a[r]<a[i]){x=a[r];a[r] =a[i];a[i] = x;}}}

java代码

import java.util.List;public class SortHeap implements Sort {@Overridepublic void sort(List<Integer> source) {for(int i = source.size()-1 ; i>0 ; i--){build_heap(source, i);switch_list_elements(source, 0, i);}}private void build_heap(List<Integer> source, int e){if(e>=source.size())return;for(int i = e; i>0 ; i--){int root = (i-1)/2;if(source.get(root)<source.get(i))switch_list_elements(source, root, i);}}private void switch_list_elements(List<Integer> source,int a, int b){int x = source.get(a);source.set(a, source.get(b));source.set(b, x);}}

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