小白进阶之优先队列排序

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优先队列排序是堆的常见应用。优先队列和堆一样，有两种形式：最大优先队列和最小优先队列。

此处是基于最大堆实现最大优先队列。最大优先队列的应用有很多，其中一个就是在共享计算机系统的作业调度。

下面是代码：

"priorityQueue.h"

#include<stdio.h>#include<limits.h>#include<stdlib.h>int heapMaximun(int *a);//返回队列中的最大值int heapExtractMax(int *a,int n);//去掉并返回最大值void heapIncreaseKey(int *a,int n,int i,int k);//将第i个数组元素的值提高到kvoid maxHeapInsert(int *a,int n,int k);//把k插入到队列中

"priorityQueue.cpp"

#include"priorityQueue.h"int parent(int i){int j=i/2;return j;}int left(int i){return 2*i;}int right(int i){return 2*i+1;}void maxHeapify(int *a,int n,int i){int l,r,max,t;l=left(i);r=right(i);if((l<=n)&&(a[l-1]>a[i-1]))max=l;else max=i;if((r<=n)&&(a[r-1]>a[max-1]))max=r;if(max!=i){t=a[i-1];a[i-1]=a[max-1];a[max-1]=t;maxHeapify(a,n,max);}}void buildMaxHeap(int *a,int n){int i;for(i=n/2;i>=0;i--){maxHeapify(a,n,i+1);}for(i=0;i<n;i++){printf("%d ",a[i]);}}int heapMaximun(int *a,int n){buildMaxHeap(a,n);return a[0];}int heapExtractMax(int *a,int n){buildMaxHeap(a,n);printf("\n");if(n<1){printf("error:heap underflow");return 0;}int max=a[0];a[0]=a[n-1];n=n-1;maxHeapify(a,n,1);for(int i=0;i<n;i++)printf("%d ",a[i]);printf("\n");return max;}void heapIncreaseKey(int *a,int n,int i,int k){buildMaxHeap(a,n);printf("\n");if(k<a[i-1]){printf("error:new key is smaller than current key.");return ;}a[i-1]=k;while((i-1>0)&&(a[parent(i)-1]<a[i-1])){int t=a[i-1];a[i-1]=a[parent(i)-1];a[parent(i)-1]=t;i=parent(i);}for(int i=0;i<n;i++)printf("%d ",a[i]);printf("\n");}void maxHeapInsert(int *a,int n,int k){buildMaxHeap(a,n);printf("\n");n=n+1;a[n]=INT_MIN;heapIncreaseKey(a,n,n,k);for(int i=0;i<n;i++)printf("%d ",a[i]);}

"main.cpp"

#include"priorityQueue.h"int main(){int *a,*b,*c,n,i,x,k;printf("Please input the number of array:\n");scanf("%d",&n);a=(int *)malloc(sizeof(int)*n);b=(int *)malloc(sizeof(int)*n);c=(int *)malloc(sizeof(int)*n);printf("Plaease input the array:\n");for(i=0;i<n;i++){scanf("%d",&a[i]);b[i]=a[i];c[i]=a[i];}int max=heapExtractMax(a,n);printf("%d\n",max);printf("Please input the number of increase element and the key:\n");scanf("%d %d",&x,&k);heapIncreaseKey(b,n,x,k);printf("Please input the key to be inserted:\n");scanf("%d",&k);maxHeapInsert(c,n,k);system("pause");return 0;}

这次实现的话，问题主要是我忘记要建堆了，就直接按照伪码来写，当然结果不对啦~
还有就是每次函数调用都要重新建堆，要不然上次函数调用就改变了数组的堆，结果当然也不对~

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