数据结构之查找

散列查找

首先我们来考虑一下散列表，散列表最核心的思想就是计算要查找的内存位置，看清楚，是位置，也就是说我们可以在O(1)的时间内找到我们需要的东西。这相对于普通查找来说，从O(N)到O(1)，是多么大的一个提升，原理我就不讲了，直接看实现，这里采用开放定址法来实现散列查找。

#include<stdio.h>#include<stdlib.h>#define SUCCESS 1#define UNSUCCESS 0#define HASHSIZE 12#define NULLKEY -32768typedef struct{    int *elem;    int count;}HashTable;int m = 0;int InitHashTable(HashTable *H){    int i;    m = HASHSIZE;    H->count = m;    H->elem=(int *)malloc(m*sizeof(int));    for(i=0;i<m;i++)        H->elem[i]= NULLKEY;    return 1;}int Hash(int key){    return key%m;}void InsertHash(HashTable *H,int key){    int addr = Hash(key);    while(H->elem[addr] != NULLKEY)        addr = (addr+1) % m;    H->elem[addr] = key;}int SearchHash(HashTable H,int key,int *addr){    *addr = Hash(key);    while(H.elem[*addr]!=key)    {        *addr = (*addr+1) % m;        if(H.elem[*addr]==NULLKEY || *addr==Hash(key))            return 0;    }    return 1;}int main(){    int A[]={12,67,56,16,25,37,22,39,15,47,48,34};    int i=0,key=39, result,addr;    HashTable H;    InitHashTable(&H);    for(i=0;i<12;i++)        InsertHash(&H,A[i]);    result = SearchHash(H,key,&addr);    for(i=0;i<12;i++)    {        SearchHash(H,A[i],&addr);        printf("%d %d\n",A[i],addr);    }    return 0;} 

二叉查找树

#include<stdio.h>#include<stdlib.h>#include<stack>#include<queue>using namespace std;typedef struct TreeNode *Tree;struct TreeNode{    int v;    Tree Left,Right;};Tree NewNode(int V){    Tree T = (Tree)malloc(sizeof(struct TreeNode));    T->v = V;    T->Left = T->Right = NULL;    return T;}Tree Insert(Tree T,int V){    if(!T)        T = NewNode(V);    else{        if(V>T->v)            T->Right = Insert(T->Right,V);        else            T->Left = Insert(T->Left,V);    }    return T;}Tree MakeTree(int N){    Tree T;    int i,V;    scanf("%d",&V);    T = NewNode(V);    for(i=1;i<N;i++){        scanf("%d",&V);        T = Insert(T,V);    }    return T;}//递归遍历 void preOrder(Tree T){    if(!T)        return ;    preOrder(T->Left);    preOrder(T->Right);    printf("%d",T->v);}//层次遍历 void LevelOrder(Tree T){    Tree t;    if(!T)        return ;    queue<Tree> q;    q.push(T);    while(!q.empty()){        t = q.front();        q.pop();        printf("%d",t->v);        if(t->Left)            q.push(t->Left);        if(t->Right)            q.push(t->Right);    }}//非递归遍历 前序 void PreRecusion(Tree T){    Tree t = T;    stack<Tree> s;    while(t || !s.empty()){        while(t){            printf("%d",t->v);            s.push(t);            t = t->Left;        }        if(!s.empty()){            t = s.top();            s.pop();            t = t->Right;        }    }}//非递归遍历 中序 void InRecusion(Tree T){    stack<Tree> s;    Tree t = T;    while(t || !s.empty()){        while(t){            s.push(t);            t = t->Left;        }        if(!s.empty()){            t = s.top();            printf("%d",t->v);            s.pop();            t = t->Right;        }    }}int main(){    Tree T;    T = MakeTree(5);    preOrder(T);    return 0;}

这段代码是关于二叉搜素树的部分，其中还包含了递归，非递归的遍历方式，非常值得一读。