PTA构造哈夫曼树

#include <malloc.h>
#include <stdio.h>
#include <string.h>

#define MinData -100000

typedef struct Heap *MinHeap;
struct Heap {
    int *Elements;    //存储堆元素的数组
    int size;    //堆当前元素个数
    int capacity;    //堆的最大容量 
};
//最小堆的创建
MinHeap create (int n); 
//插入
void Insert ( MinHeap H, int item );
//删除
int Delete (MinHeap H);

int main() {
    MinHeap H;
    int n, k, m, flag, item;
    int weight, pindu;
    weight = pindu = 0;    
    char name[100];
    scanf("%d", &n);
    H = create (n);
    int i;
    for (i=0; i<n; i++) {
        scanf("%s %d", &name, &item);
        pindu += item;
        Insert (H, item);
    }
    while(1){
        int num1 = Delete(H);
        int num2 = Delete(H);
        if(num2 == -1){    //最小堆为空 
            printf("%.5f", 1.0*weight/pindu);
            return 0;
        }
        int num = num1 + num2;
        Insert(H, num);
        weight += num;
    }
    return 0;
}

//最小堆的创建
MinHeap create (int n) {
    MinHeap H = (MinHeap)malloc(sizeof(struct Heap));
    H->Elements = (int*)malloc( (n+1) * sizeof(H->Elements));
    H->size = 0;
    H->capacity = n;
    H->Elements[0] = MinData;
    return H;
}

//插入
void Insert ( MinHeap H, int item ) {
    int i;
    i = ++H->size;
    for ( ; H->Elements[i/2]>item; i/=2){
        H->Elements[i] = H->Elements[i/2];
    }
    H->Elements[i] = item;
}

//删除
int Delete (MinHeap H) {
    if(H->size == 0){
        return -1;
    }
    int parent = 0, child = 0, minitem, t;
    minitem = H->Elements[1];
    t = H->Elements[H->size--];
    for (parent=1; parent*2<=H->size; parent=child) {
        child = parent * 2;
        if ((child != H->size) && (H->Elements[child] > H->Elements[child+1]))
            child++;
        if (t < H->Elements[child]){
            break;
        }
        else
            H->Elements[parent] = H->Elements[child];
    }
    H->Elements[parent] = t;
    return minitem;
}