冲突解决策略是定义一个序列F(i)=ri，其中r0=0且r1,r2……rN是前N个整数的随机排列（每个整数恰好出现一次）

数据结构与算法分析——c语言描述 练习5.5e  答案

hashQuad.c

#include"hashQuad.h"
#include"fatal.h"
#include<math.h>
#include<string.h>
#define MinTableSize 5

enum KindOfEntry { Legitimate, Empty, Deleted };



struct HashEntry {
	ElementType element;
	enum KindOfEntry info;
};

typedef struct HashEntry Cell;

struct HashTbl {
	int tableSize;
	int hasInsertedNum;
	Cell *theCells;//数组
	int* randomArr;
};



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

static 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;
	}
}

static int hash(ElementType key, int tableSize) {
	return key % (tableSize);
}
static int isPrime(int num) {
	for (int i = 2; i <= sqrt(num); i++)
		if (num%i == 0)
			return 0;
	return 1;
}
static int nextPrime(int num) {
	int i = num;
	while (!isPrime(i))
		i++;
	return i;
}

int isLegitimate(Position pos, HashTable h) {
	return h->theCells[pos].info == Legitimate;
}


HashTable initializeTable(int tableSize) {
	HashTable h;
	int i;
	if (tableSize < MinTableSize) {
		Error("Table size too small");
		return NULL;
	}
	h = malloc(sizeof(struct HashTbl));
	if (h == NULL)
		FatalError("Out of space!!!");
	h->tableSize = nextPrime(tableSize);
	h->theCells = malloc(sizeof(Cell)*h->tableSize);
	h->hasInsertedNum = 0;
	h->randomArr = malloc(sizeof(int)*h->tableSize);
	getRandomInt(h->randomArr, h->tableSize);
	if (h->theCells == NULL)
		FatalError("Out of space!!!");
	for (i = 0; i < h->tableSize; i++) {
		h->theCells[i].info = Empty;
	}
	return h;
}

void destroyTable(HashTable h) {
	free(h->randomArr);
	free(h->theCells);
	free(h);
}

Position find(ElementType key, HashTable h) {
	Position currentPos = hash(key, h->tableSize);


	int collisionNum = 0;

	while (h->theCells[currentPos].info != Empty && h->theCells[currentPos].element != key) {
		currentPos = (currentPos + h->randomArr[collisionNum++]) % h->tableSize;
	}
	return currentPos;
}

HashTable insert(ElementType key, HashTable h) {
	if ((double)h->hasInsertedNum / h->tableSize > 0.5)
		h = rehash(h);
	Position pos = find(key, h);
	if (h->theCells[pos].info != Legitimate) {
		h->theCells[pos].element = key;
		h->theCells[pos].info = Legitimate;
		h->hasInsertedNum++;
	}
	return h;
}

HashTable rehash(HashTable h) {
	HashTable newH = initializeTable(h->tableSize * 2);
	for (int i = 0; i < h->tableSize; i++)
		if (h->theCells[i].info == Legitimate)
			insert(h->theCells[i].element, newH);
	destroyTable(h);
	return newH;
}



ElementType retrive(Position p, HashTable h) {
	return h->theCells[p].element;
}

main.c

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



#define N 111
int randIntArr[N];//这么大的数组放在全局变量上，如果放在main里就是放在程序的堆上，运行时再分配。放在外面就是编译时就分配在静态数据那。



int main() {
	for (int i = 0; i < N; i++)
		randIntArr[i] = rand();
	HashTable h = initializeTable(100);

	for (int i = 0; i < N; i++)
		h = insert(randIntArr[i], h);

	destroyTable(h);
}