第十五周项目1 验证算法（3）交换排序之冒泡排序

用序列{57, 40, 38, 11, 13, 34, 48, 75, 6, 19, 9, 7}作为测试数据，运行并本周视频中所讲过的算法对应 程序，观察运行结果并深刻领会算法的思路和实现方法：

冒泡排序

#include <stdio.h>#define MaxSize 20typedef int KeyType;    //定义关键字类型typedef char InfoType[10];typedef struct          //记录类型{    KeyType key;        //关键字项    InfoType data;      //其他数据项,类型为InfoType} RecType;              //排序的记录类型定义void BubbleSort(RecType R[],int n){    int i,j,k;    RecType tmp;    for (i=0; i<n-1; i++)    {        for (j=n-1; j>i; j--)   //比较,找出本趟最小关键字的记录            if (R[j].key<R[j-1].key)            {                tmp=R[j];  //R[j]与R[j-1]进行交换,将最小关键字记录前移                R[j]=R[j-1];                R[j-1]=tmp;            }        printf("i=%d: ",i);        for (k=0; k<n; k++)            printf("%d ",R[k].key);        printf("\n");    }}int main(){    int i,n=10;    RecType R[MaxSize];    KeyType a[]= {9,8,7,6,5,4,3,2,1,0};    for (i=0; i<n; i++)        R[i].key=a[i];    printf("排序前:");    for (i=0; i<n; i++)        printf("%d ",R[i].key);    printf("\n");    BubbleSort(R,n);    printf("排序后:");    for (i=0; i<n; i++)        printf("%d ",R[i].key);    printf("\n");    return 0;}
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改进的算法(一趟冒泡没有交换，即时结束排序过程)

#include <stdio.h>#define MaxSize 20typedef int KeyType;    //定义关键字类型typedef char InfoType[10];typedef struct          //记录类型{    KeyType key;        //关键字项    InfoType data;      //其他数据项,类型为InfoType} RecType;              //排序的记录类型定义void BubbleSort1(RecType R[],int n){    int i,j,k,exchange;    RecType tmp;    for (i=0; i<n-1; i++)    {        exchange=0;        for (j=n-1; j>i; j--)   //比较,找出最小关键字的记录            if (R[j].key<R[j-1].key)            {                tmp=R[j];  //R[j]与R[j-1]进行交换,将最小关键字记录前移                R[j]=R[j-1];                R[j-1]=tmp;                exchange=1;            }        printf("i=%d: ",i);        for (k=0; k<n; k++)            printf("%d ",R[k].key);        printf("\n");        if (exchange==0)    //中途结束算法            return;    }}int main(){    int i,n=10;    RecType R[MaxSize];    KeyType a[]= {0,1,7,2,5,4,3,6,8,9};    for (i=0; i<n; i++)        R[i].key=a[i];    printf("排序前:");    for (i=0; i<n; i++)        printf("%d ",R[i].key);    printf("\n");    BubbleSort1(R,n);    printf("排序后:");    for (i=0; i<n; i++)        printf("%d ",R[i].key);    printf("\n");    return 0;}