基于链表的基数排序v2.0

数据结构与算法分析——c语言描述 第三章的基数排序

之前写过了，但当时发现时间主要用在找到最后一个元素，今天重新写了，保存一个指向最后结点的指针。

last指针的初始值要非常小心啊，一开始我是初始值为NULL。这样有一个问题，就是插入第一个元素的时候（头结点版链表），last指针是不会更新的！islast函数我是判断是否和last指针相等。debug了一整天，一开始想都想不明白，后来才大概摸到方向。智商捉急。。。。

list.h

typedef int ElementType;#ifndef _List_H#define _List_Hstruct Node;struct ListRecord;typedef struct ListRecord *VariantList;typedef struct Node *PtrToNode;typedef PtrToNode List;typedef PtrToNode Position;VariantList createVariantList();void MakeEmpty(VariantList varList);int IsEmpty(VariantList varList);int IsLast(Position P, VariantList varList);Position Find(ElementType X, VariantList varList);void Delete(ElementType X, VariantList varList);Position FindPrevious(ElementType X, VariantList varList);void Insert(ElementType X, VariantList varList, Position P);void DeleteVariantList(VariantList varList);Position Header(VariantList varList);Position First(VariantList varList);Position Advance(Position P);ElementType Retrieve(Position P);void InsertFront(ElementType X, VariantList varList);void InsertBack(ElementType X, VariantList varList);#endif

list.c

#include"list.h"#include"fatal.h"struct ListRecord {List L;PtrToNode Last;};struct Node{ElementType Element;Position Next;};static void DeleteList(List L) {Position p;p = L->Next;L->Next = NULL;while (p != NULL) {Position tmp;tmp = p->Next;free(p);p = tmp;}}VariantList createVariantList() {VariantList varList = malloc(sizeof(struct ListRecord));varList->L = malloc(sizeof(struct Node));if (varList->L == NULL)Error("out of memory");varList->L->Next = NULL;varList->Last = varList->L;return varList;}void MakeEmpty(VariantList varList) {if (varList->L != NULL)DeleteList(varList->L);varList->Last = varList->L;}int IsEmpty(VariantList varList) {return varList->L->Next == NULL;}int IsLast(Position P, VariantList varList) {return P == varList->Last;}Position Find(ElementType X, VariantList varList) {Position P;P = varList->L->Next;while (P != NULL && P->Element != X){P = P->Next;}return P;}void Delete(ElementType X, VariantList varList) {Position P;P = FindPrevious(X, varList);if (!IsLast(P, varList)) {Position TmpCell = P->Next;if (IsLast(TmpCell,varList))varList->Last = P;P->Next = TmpCell->Next;free(TmpCell);}}Position FindPrevious(ElementType X, VariantList varList) {Position P;P = varList->L;while (P->Next != NULL&&P->Next->Element != X)P = P->Next;return P;}void Insert(ElementType X, VariantList varList, Position P) {Position tmpCell;tmpCell = malloc(sizeof(struct Node));if (tmpCell == NULL)FatalError("Out of space!!");tmpCell->Element = X;tmpCell->Next = P->Next;if (IsLast(P,varList))varList->Last = tmpCell;P->Next = tmpCell;}void DeleteVariantList(VariantList varList) {MakeEmpty(varList);free(varList->L);free(varList);}Position Header(VariantList varList) {return varList->L;}Position First(VariantList varList) {return varList->L->Next;}Position Advance(Position P) {return P->Next;}ElementType Retrieve(Position P) {return P->Element;}void InsertFront(ElementType X, VariantList varList) {Insert(X, varList, varList->L);}void InsertBack(ElementType X, VariantList varList) {if (IsEmpty(varList)) {Insert(X, varList, varList->L);}else{Insert(X, varList, varList->Last);}}

main.c

#include"list.h"#include<stdio.h>#define BUCKETS 10 //桶的数量#define N 10//需要排序数字数量#define BITS 3 //位数void radixSort(int arr[]);int getDigital(int x, int cnt);void print(int arr[]);int main() {int arr[N] = { 64, 8, 216, 512, 27, 729, 0, 1, 343, 125 };print(arr);radixSort(arr);print(arr);}void radixSort(int arr[]) {VariantList bucket[BUCKETS];int i, j, k;for (i = 0; i < BUCKETS; i++) {bucket[i] = createVariantList();}for (i = 0; i < BITS; i++) {for (j = 0; j < BUCKETS; j++)MakeEmpty(bucket[j]);for (k = 0; k < N; k++) {InsertBack(arr[k], bucket[getDigital(arr[k], i)]);}for (int i = 0, k = 0; i < N; i++) {Position p;p = First(bucket[i]);while (p != NULL) {arr[k++] = Retrieve(p);p = Advance(p);}}}for (i = 0; i<BUCKETS; ++i)DeleteVariantList(bucket[i]);}int getDigital(int x, int cnt) {for (int i = 0; i < cnt; i++)x /= 10;return x % 10;}void print(int arr[]) {for (int i = 0; i < N; i++) {printf("%d ", arr[i]);}printf("\n");}