首页 > 技术文章 > PTA 最小堆插入元素和删除堆顶(无哨兵元素) (20分)

p1967914901 2020-05-02 15:51 原文

PTA 最小堆插入元素和删除堆顶(无哨兵元素) (20分)

对于给定的最小堆(优先队列),分别实现插入元素和删除堆顶的函数。

函数接口定义:

int insertIntoHeap(struct Heap* h, int x);  // 向堆中插入元素x
int deleteMin(struct Heap* h, int* pElement);  //将堆顶元素拷贝到pElement所指变量并删除堆顶元素  

其中,h、x和pElement为参数,h是堆结构体指针,x是待插入元素的值,pElement指向的变量用于存放删除的堆顶元素。

堆结构体定义如下:

struct Heap{
    int *data;  // 堆元素存储空间指针,堆元素从data[1]开始存放,data[0]不使用,无哨兵元素
    int capacity; // 堆容量
    int size; // 堆元素数量
};

裁判测试程序样例:

#include <stdio.h>
#include <stdlib.h>
struct Heap{
    int *data;
    int capacity;
    int size;
};
struct Heap* initHeap(int capacity){   // 初始化堆
    struct Heap* h;
    h = (struct Heap*)malloc(sizeof(struct Heap));
    if(!h) return NULL;
    h->data = (int*)malloc(sizeof(int)*capacity+1);
    if(h->data == NULL){
        free(h);
        return NULL;
    }
    h->capacity = capacity;
    h->size = 0;
    return h;
};
void printHeap(struct Heap* h){  // 打印堆元素
    /* 细节省略 */
}
int insertIntoHeap(struct Heap* h, int x);
int deleteMin(struct Heap* h, int* pElement);
int main(){
    struct Heap *h;
    int n;
    scanf("%d", &n);   // 输入堆容量
    h = initHeap(n);
    int op, x;
    scanf("%d", &op);
    while(op){    // 输入操作: -1表示删除   1表示插入   0表示结束
        if(op == 1){
            scanf("%d", &x);
            printf("Insertion %s. ", insertIntoHeap(h, x) ? "succeeded" : "failed" );
            printHeap(h);
        }
        else{
            if (deleteMin(h, &x) ) printf("%d deleted. ", x);
            else printf("Deletion failed. ");
            printHeap(h);
        }
        scanf("%d", &op);
    }
    return 0;
}

/*你提交的代码将被嵌在这里 */

输入样例:

对于样例测试程序规定的输入格式:

3
1 10
1 20
1 5
1 40
-1
-1
-1
-1
0

输出样例:

样例测试程序的输出:

Insertion succeeded. 10, 
Insertion succeeded. 10, 20, 
Insertion succeeded. 5, 20, 10, 
Insertion failed. 5, 20, 10, 
5 deleted. 10, 20, 
10 deleted. 20, 
20 deleted. 
Deletion failed. 

【程序实现】

int insertIntoHeap(struct Heap* h, int x) {
    if (h->capacity == h->size) return 0;
    int i = ++h->size;
    for(; h->data[i/2] > x && i > 1; i /= 2)
        h->data[i] = h->data[i/2];
    h->data[i] = x;
    return 1;
}
int deleteMin(struct Heap* h, int* pElement) {
    if(!h->size) return 0;
    *pElement = h->data[1];
    int t = h->data[h->size--];
    int parent, child;
    for(parent = 1; parent*2 <= h->size; parent = child) {
        child = parent*2;
        if(child != h->size && h->data[child] > h->data[child+1])
            child++;
        if(h->data[child] > t) break;
        else h->data[parent] = h->data[child];
    }
    h->data[parent] = t;
    return 1;
}

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