数据结构实践项目——查找（一）

1. 折半查找

#include <stdio.h>#define MAXL 100typedef int KeyType;typedef char InfoType[10];typedef struct{    KeyType key;                //KeyType为关键字的数据类型    InfoType data;              //其他数据} NodeType;typedef NodeType SeqList[MAXL];     //顺序表类型int BinSearch(SeqList R,int n,KeyType k){    int low=0,high=n-1,mid;    while (low<=high)    {        mid=(low+high)/2;        if (R[mid].key==k)      //查找成功返回            return mid+1;        if (R[mid].key>k)       //继续在R[low..mid-1]中查找            high=mid-1;        else            low=mid+1;          //继续在R[mid+1..high]中查找    }    return 0;}int main(){    int i,n=10;    int result;    SeqList R;    KeyType a[]= {1,3,9,12,32,41,45,62,75,77},x=75;    for (i=0; i<n; i++)        R[i].key=a[i];    result = BinSearch(R,n,x);    if(result>0)        printf("序列中第 %d 个是 %d\n",result, x);    else        printf("木有找到！\n");    return 0;}
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2.递归的折半查找算法

#include <stdio.h>#define MAXL 100typedef int KeyType;typedef char InfoType[10];typedef struct{    KeyType key;                //KeyType为关键字的数据类型    InfoType data;              //其他数据} NodeType;typedef NodeType SeqList[MAXL];     //顺序表类型int BinSearch1(SeqList R,int low,int high,KeyType k){    int mid;    if (low<=high)      //查找区间存在一个及以上元素    {        mid=(low+high)/2;  //求中间位置        if (R[mid].key==k) //查找成功返回其逻辑序号mid+1            return mid+1;        if (R[mid].key>k)  //在R[low..mid-1]中递归查找            BinSearch1(R,low,mid-1,k);        else              //在R[mid+1..high]中递归查找            BinSearch1(R,mid+1,high,k);    }    else        return 0;}int main(){    int i,n=10;    int result;    SeqList R;    KeyType a[]= {1,3,9,12,32,41,45,62,75,77},x=75;    for (i=0; i<n; i++)        R[i].key=a[i];    result = BinSearch1(R,0,n-1,x);    if(result>0)        printf("序列中第 %d 个是 %d\n",result, x);    else        printf("木有找到！\n");    return 0;}