左式堆

数据结构与算法分析——c语言描述 第六章

代码不难。反倒是理解merge挺难的。

一个左式堆，它的子树也是左式堆。合并就是不断递归，直到找到一个空指针，然后合并。并且判断左边的npl是不是大于等于右边的npl。在一层一层返回。所以合并的又是一个左式堆。

leftheap.h

#ifndef _LeftHeap_H
#define _LeftHeap_H
typedef int ElementType;

struct TreeNode;
typedef struct TreeNode *PriorityQueue;

PriorityQueue initialize(void);
ElementType findMin(PriorityQueue h);
int isEmpty(PriorityQueue h);
PriorityQueue merge(PriorityQueue h1, PriorityQueue h2);
#define insert(X,H) (H=insert1((X),H))
PriorityQueue insert1(ElementType X, PriorityQueue h);
PriorityQueue deleteMin1(PriorityQueue h);
#define deleteMin(H) (H=deleteMin1(H))

#endif // !_BinHeap_H

leftheap.c

#include"leftheap.h"
#include"fatal.h"

struct TreeNode {
ElementType element;
PriorityQueue left;
PriorityQueue right;
int np1;
};

PriorityQueue initialize(void) {
return NULL;
}

ElementType findMin(PriorityQueue h) {
if (isEmpty(h))
Error("EMPTY HEAP");
return h->element;
}

int isEmpty(PriorityQueue h) {
return h == NULL;
}

static PriorityQueue merge1(PriorityQueue h1, PriorityQueue h2) {
if (h1->left == NULL) {
h1->left = h2;
return h1;
}
else {
h1->right= merge(h1->right, h2);
if (h1->right->np1 > h1->left->np1) {
PriorityQueue temp;
temp = h1->right;
h1->right = h1->left;
h1->left = temp;
}
h1->np1 = h1->right->np1 + 1;
return h1;
}
}

PriorityQueue merge(PriorityQueue h1, PriorityQueue h2) {
if (h1 == NULL)
return h2;
else if (h2 == NULL)
return h1;
else {
if (h1->element < h2->element)
return merge1(h1, h2);
else
return merge1(h2, h1);
}
}

PriorityQueue insert1(ElementType X, PriorityQueue h) {
PriorityQueue newNode = malloc(sizeof(struct TreeNode));
newNode->element = X;
newNode->left = NULL;
newNode->right = NULL;
newNode->np1 = 0;
return merge(newNode, h);
}

PriorityQueue deleteMin1(PriorityQueue h) {
PriorityQueue temp1 = h->left;
PriorityQueue temp2 = h->right;
free(h);
return merge(temp1, temp2);

}

main.c

#include"leftheap.h"
#include<stdlib.h>
#include<stdio.h>

int RandInt(int i, int j) {
int temp;
temp = (int)(i + (1.0*rand() / RAND_MAX)*(j - i));
return temp;
}

void getRandomInt(int *A, int n) {
for (int i = 0; i < n; i++) {
A[i] = i + 1;
}

for (int i = 1; i < n; i++) {
//std::swap(A[i], A[RandInt(0, i)]);
int randAdrr = RandInt(0, i);
int t = A[i];
A[i] = A[randAdrr];
A[randAdrr] = t;
}
}

int a[99999999];

int main() {
int n;
scanf("%d", &n);
//int *a = malloc(sizeof(int)*n);
//if (a == NULL)
//	fprintf(stderr,"out of memory");
getRandomInt(a, n);

PriorityQueue h1 = initialize();
PriorityQueue h2 = initialize();
int i;
for (i = 0; i < n / 2; i++)
insert(a[i], h1);
for (; i < n; i++)
insert(a[i], h2);

PriorityQueue h = merge(h1, h2);

for (int i = 0; i < n; i++) {
printf("%d ", findMin(h));
deleteMin(h);
}

//destroy(h);
//free(a);

}