pta Percolate Up and Down

Write the routines to do a “percolate up” and a “percolate down” in a binary min-heap.
Format of functions:

void PercolateUp( int p, PriorityQueue H );void PercolateDown( int p, PriorityQueue H );

where int p is the position of the element, and PriorityQueue is defined as the following:

typedef struct HeapStruct *PriorityQueue;struct HeapStruct {    ElementType  *Elements;    int Capacity;    int Size;};

Sample program of judge:

#include <stdio.h>#include <stdlib.h>typedef int ElementType;#define MinData -1typedef struct HeapStruct *PriorityQueue;struct HeapStruct {    ElementType  *Elements;    int Capacity;    int Size;};PriorityQueue Initialize( int MaxElements ); /* details omitted */void PercolateUp( int p, PriorityQueue H );void PercolateDown( int p, PriorityQueue H );void Insert( ElementType X, PriorityQueue H ) {    int p = ++H->Size;    H->Elements[p] = X;    PercolateUp( p, H );}ElementType DeleteMin( PriorityQueue H ) {     ElementType MinElement;     MinElement = H->Elements[1];    H->Elements[1] = H->Elements[H->Size--];    PercolateDown( 1, H );    return MinElement; }int main(){    int n, i, op, X;    PriorityQueue H;    scanf("%d", &n);    H = Initialize(n);    for ( i=0; i<n; i++ ) {        scanf("%d", &op);        switch( op ) {        case 1:            scanf("%d", &X);            Insert(X, H);            break;        case 0:            printf("%d ", DeleteMin(H));            break;        }    }    printf("\nInside H:");    for ( i=1; i<=H->Size; i++ )        printf(" %d", H->Elements[i]);    return 0;}/* Your function will be put here */

Sample Input:

91 101 51 201 91 11 400

Sample Output:

2 1 4 Inside H: 5 10 9

思路：
题目让实现最小堆的插入维护和删除维护。只要记住最小的在上面就行。
另外要注意down的时候可能只有一个儿子。

代码：

void PercolateDown( int p, PriorityQueue H ){       if(p<<1 > H->Size)return;    int replace;    if(p<<1+1 <= H->Size)replace = (H->Elements[p<<1] < H->Elements[p<<1+1] ? p<<1 : p<<1+1);    else replace = p<<1;    if(H->Elements[replace] < H->Elements[p])    {        int mid = H->Elements[replace];        H->Elements[replace] = H->Elements[p];        H->Elements[p] = mid;        PercolateDown( replace, H );    }}void PercolateUp( int p, PriorityQueue H ){    if(p == 1)return;    if(p&1)    {        if(H->Elements[(p-1)>>1] > H->Elements[p])        {            int mid = H->Elements[(p-1)>>1];            H->Elements[(p-1)>>1] = H->Elements[p];            H->Elements[p] = mid;            PercolateUp( (p-1)>>1, H );        }    }    else    {        if(H->Elements[p>>1] > H->Elements[p])        {            int mid = H->Elements[p>>1];            H->Elements[p>>1] = H->Elements[p];            H->Elements[p] = mid;            PercolateUp( p>>1, H );        }    }}