数据结构：线性表查找的三种方式

只要是静态查找表即可

#define ElemType int
typedef struct {
ElemType *d;
int length;
}SSTable;

顺序查找 S(n)=O(1) 哨兵空间

int Search_Seq(SSTable t,ElemType key)
{
    t.d[0]=key;
    for (int i = t.length; i >0 ; i--) {
        if(t.d[i]==t.d[0])
        {
            return i;
        }
    }
    return 0;
}

---

折半查找（二分查找）：要求必须是顺序存储，且元素内有序

非递归

int Search_bin_notDG(SSTable t,ElemType key)
{
    int low=1,high=t.length-1;
    while (low<=high)
    {
        int mid=(high+low)/2;
        if(t.d[mid]==key)
        {return mid;}
        else if(t.d[mid]>key)
        {
            high=mid-1;
        } else{
            low=mid+1;
        }
    }
    return 0;
}

递归

int Search_bin_DG(SSTable t,ElemType key,int high,int low)
{
    if(low>high)
    {return 0;}
    int mid=(low+high)/2;
    if(t.d[mid]==key)
    {return mid;}
    else if(t.d[mid]<key)
    {
        Search_bin_DG(t,key,high,mid+1);
    }
    else
    {
        Search_bin_DG(t,key,mid-1,low);
    }


}

分块查找：主要是利用索引表进行查找，块间有序，块内有无序决定块内查找方式