编程珠玑第十三章----查找

int find1(int *array,int n,int val)
{
if (n<=0)
{
return -1;
}

for (int i=0;i<n;i++)
{
if (val==array[i])
{
return i;
}
}

return -1;
}

int find2(int *array,int n,int val)
{
if (n<=0)
{
return -1;
}

int begin=0,end=n-1,mid;
while(begin<=end)
{
mid=(begin+end)/2;
if (array[mid]==val)
return mid;
else if(array[mid]>val)
end=mid-1;
else
begin=mid+1;
}

return -1;
}

//二叉查找树数据结构
typedef struct Btree
{
int data;
Btree *left;
Btree *right;
}*PBTree;

//创建二叉查找树，返回树的根节点
PBTree CreateBTree(int *array,int n)
{
PBTree root=new Btree;
root->data=array[0];
root->left=NULL;
root->right=NULL;

PBTree current,back,pNew;
for (int i=1;i<n;i++)
{
pNew=new Btree;
pNew->data=array[i];
pNew->left=pNew->right=NULL;
current=root;
while(current!=NULL)   //找到合适的插入位置
{
back=current;
if(current->data>array[i])
current=current->left;
else
current=current->right;
}
if(back->data>array[i])
back->left=pNew;
else
back->right=pNew;
}

return root;
}

//利用二叉查找树进行递归查找
bool find3(PBTree root,int val)
{
if (root==NULL)
return false;
if (root->data==val)
return true;
else if(root->data>val)
return find3(root->left,val);
else
return find3(root->right,val);
}

#define MAX 10

//链表数据结构
typedef struct list
{
int data;
list *next;
}*pList;

list hashtable[MAX];  ///链式法解决地址冲突，MAX个带头节点的hash链表

//除留取余法
int hashFunc(int n)
{
return n%MAX;
}

//创建hash链表
void createhash(int *array,int n)
{
pList p,pNew;
for (int i=0;i<n;i++)
{
pNew=new list;
pNew->data=array[i];
pNew->next=NULL;

int pos=hashFunc(array[i]);
p=hashtable[pos].next;

if (p!=NULL)         //将新的节点插入到头结点的后面
{
pNew->next=p;
hashtable[pos].next=pNew;
}
else
{
hashtable[pos].next=pNew;
}
}
}

//hash查找
bool SearchHash(int val)
{
int pos=hashFunc(val);        //找出在哪个hash链表
pList p=hashtable[pos].next;  //遍历对应的链表
while(p!=NULL)
{
if(p->data==val)
return true;
p=p->next;
}

return false;
}

//遍历hashtable
void TraverseHashtable()
{
for (int m=0;m<MAX;m++) //一次遍历每个链表里面的内容
{
pList p1=hashtable[m].next;
while(p1!=NULL)
{
cout<<p1->data<<" ";
p1=p1->next;
}
}
cout<<endl;
}