顺序查找和折半查找

一、顺序查找

1.顺序查找表

//顺序查找表
typedef  struct{
   ElemType *elem;
   int Tablelen;
}SSTable;

2.顺序查找代码

//不带哨兵版本
int Search_Seq(SSTable ST, ElemType key)
{
    for (int i=0;i
        return  i==ST.Tablelen?-1:i;
    }
}
 
 
//带哨兵
int Search_Seq(SSTable ST, ElemType key)
{
    ST.elem[0]=key;
    int i;
    for ( i=ST.Tablelen;ST.elem[i]!=key;i--);
    return i;
 
}

二、折半查找

int Binary_Searh(SSTable ST, ElemType key)
{
    int low=0,high=ST.Tablelen-1,mid;
    while (low<=high) {
        mid = (low+high)/2;
        if(ST.elem[mid]==key)
            return mid;
         else if(ST.elem[mid]>key) {
            high=mid-1;
        }
        else {
            low=mid+1;
        }
    }
    return -1;
}