折半查找和顺序查找

折半查找（二分）：

#include 
#include 
#define MAX_NUM 100
typedef struct
{
    int key;
} ElemType;
typedef struct
{
    ElemType elem[MAX_NUM];
    int length;
} SSTable;
int s(SSTable st,int key)
{
    int i;
    int ans=0;
    int l=1,r=st.length,mid=0;
    while (l<=r)
    {
        mid=(l+r)/2;
        ans++;
        if (key>st.elem[mid].key)
            l=mid+1;
        else if (key1;
        else
        {
            printf("查找次数：%d\n",ans);
            return mid;
        }
    }
    printf("查找次数：%d\n",ans);
    return 0;
}
int main()
{
    int n,i,t;
    SSTable st;
    scanf("%d",&n);
    st.length=n;
    for (i=1; i<=n; i++)
        scanf("%d",&st.elem[i].key);
    scanf("%d",&t);
    t=s(st,t);
    if (t==0)
        printf("不存在要查找的数据\n");
    else printf("查找数据的位置：%d\n",t);
    return 0;
}

顺序查找：

#include 
#include 
#define MAX_NUM 100
typedef struct
{
    int key;
} ElemType;
typedef struct
{
    ElemType elem[MAX_NUM];
    int length;
} SSTable;
int s(SSTable st,int key)
{
    int i;
    int ans=0;
    st.elem[0].key=key;
    for (i=st.length; i>=1; i--)
    {
        ans++;
         if (st.elem[i].key==key)
         {
             printf("查找次数：%d\n",ans);
             return i;
         }
    }
    printf("查找次数：%d\n",st.length);
    return 0;
}
int main()
{
    int n,i,t;
    SSTable st;
    scanf("%d",&n);     //输入数据的个数
    st.length=n;
    for (i=1; i<=n; i++)
        scanf("%d",&st.elem[i].key);
    scanf("%d",&t);
    t=s(st,t);
    if (t==0)
        printf("不存在要查找的数据\n");
    else printf("查找数据的位置：%d\n",t);
    return 0;
}