一、Xmind整理:
二、课上练习:
练习1:时间复杂度
时间复杂度:只保留最高阶
f(n)=3*n^2+n^2+100+n
T(n)=O(3*n^3+n^2+100+n)=O(3*n^3)=O(n^3)
1>O(1):常数阶
int t=a; 1
a=b; 1
a=t; 1
f(n)=3
T(n)=O(3)=O(3*n^0)=O(n^0)=O(1)
2>O(n): 线性阶
for(int i=1;i<=n;i++) n+1
{
printf("1"); n
}
f(n)=n*2+1=n
3> O(n^2): 平方阶
for(int i=1;i<=n;i++) n+1
{
for(int j=1;j<=n;j++) n*(n+1)
{
printf("1"); n*n
}
}
f(n)=2*n^2+2*n+1--->n^2
for(int i=1;i<n;i++) n
{
for(int j=0;j<n-i;j++) (n-1)*(n-i)
{
printf("1"); (n-1)*(n-i-1)
}
}
f(n)=n^2
4> O(n^3): 立方阶
for(int i=1;i<=n;i++) n+1
{
for(int j=1;j<=m;j++) n*(m+1)
{
for(int k=1;k<=n;k++) n*m*(n+1)
{
printf("1"); n*m*n
}
}
}
f(n)=2*n^2*m+2*n*m+1=2*n^2*m=n^2*m
5>O(log2n):对数阶
int i=1; 1
int n=8; 1
while(i<n) log2 n +1
{
i*=3; 123 log2 n
}
f(n)=2*log2 n +3=log2n
三、课后作业:
1.顺序表按下标/数据元素实现增、删、改、查
head.h
//预处理命令
//函数声明
//全局变量
#ifndef __HEAD_H__
#define __HEAD_H__
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#define MAXSIZE 8
typedef int datatype;
//定义顺序表
typedef struct
{
//顺序表长度
int len;
//数据元素
datatype data[MAXSIZE];
}Seqlist;
Seqlist *create_list();
int full_list(Seqlist *list);
int insert_rear(datatype e,Seqlist *list);
int empty(Seqlist *list);
void output(Seqlist *list);
int delete_rear(Seqlist *list);
datatype search_by_sub(int sub,Seqlist *list);
int update_by_sub(Seqlist *list,int sub,datatype e);
int insert_by_sub(Seqlist *list,int sub,datatype e);
int delete_by_sub(Seqlist *list,int sub);
int search_by_data(datatype key,Seqlist *list);
int update_by_data(datatype key,datatype e,Seqlist *list);
int insert_by_data(datatype key,datatype e,Seqlist *list);
int delete_by_data(datatype key,Seqlist *list);
#endif
test.c
//写自定义函数
#include "head.h"
/*
* function: 顺序表在堆区申请空间
* @param [ in]
* @param [out]
* @return
*/
Seqlist *create_list()
{
Seqlist *list=(Seqlist *)malloc(sizeof(Seqlist));
if(NULL==list)
{
return NULL;
}
list->len=0; //顺序表长度清零
memset(list->data,0,sizeof(list->data));
}
/*
* function: 判断顺序表满
* @param [ in]
* @param [out]
* @return 满返回-1 不满返回0
*/
int full_list(Seqlist *list)
{
return list->len==MAXSIZE?-1:0;
}
/*
* function: 尾插,插入一个
* @param [ in]
* @param [out]
* @return 成功返回0 失败返回-1
*/
int insert_rear(datatype e,Seqlist *list)
{
if(NULL==list||full_list(list))
{
printf("insert rear error\n");
return -1;
}
list->data[list->len]=e;
list->len++;
return 0;
}
/*
* function: 顺序表为空
* @param [ in]
* @param [out]
* @return 空返回-1 非空返回0
*/
int empty(Seqlist *list)
{
return list->len==0?-1:0;
}
/*
* function: 输出
* @param [ in]
* @param [out]
* @return
*/
void output(Seqlist *list)
{
if(NULL==list||empty(list))
{
puts("output error");
return;
}
for(int i=0;i<list->len;i++)
{
printf("%d\t",list->data[i]);
}
puts("");
}
/*
* function: 尾部删除
* @param [ in]
* @param [out]
* @return 成功返回0 失败返回-1
*/
int delete_rear(Seqlist *list)
{
if(NULL==list||empty(list))
{
puts("delete rear error");
return -1;
}
printf("delete element is:%d\n",list->data[list->len+1]);
list->len--;
}
/*
* function: 按下标查找
* @param [ in]
* @param [out]
* @return 成功返回查找的值 失败返回-1
*/
datatype search_by_sub(int sub,Seqlist *list)
{
//1.判断顺序表是否存在
//2.判断顺序表是否为空
//3.判断下标是否合法
if(NULL==list||empty(list)||sub<0||sub>=list->len)
{
puts("search element error");
return -1;
}
return list->data[sub];
}
/*
* function: 按下标修改
* @param [ in]
* @param [out]
* @return 成功返回0 失败返回-1
*/
int update_by_sub(Seqlist *list,int sub,datatype e)
{
if(NULL==list||empty(list)||sub<0||sub>=list->len)
{
return -1;
}
list->data[sub]=e;
return 0;
}
/*
* function: 按下标插入
* @param [ in]
* @param [out]
* @return 成功返回0 失败返回-1
*/
int insert_by_sub(Seqlist *list,int sub,datatype e)
{
if(NULL==list||full_list(list)||sub<0||sub>list->len)
{
printf("insert error\n");
return -1;
}
for(int i=list->len-1;i>=sub;i--)
{
list->data[i+1]=list->data[i];
}
list->data[sub]=e;
list->len++;
return 0;
}
/*
* function: 按下标删除
* @param [ in]
* @param [out]
* @return 成功返回0 失败返回-1
*/
int delete_by_sub(Seqlist *list,int sub)
{
if(NULL==list||empty(list)||sub<0||sub>=list->len)
{
printf("delete error\n");
return -1;
}
for(int i=sub;i<=list->len-1;i++)
{
list->data[i]=list->data[i+1];
}
list->len--;
return 0;
}
/*
* function: 按元素查找
* @param [ in]
* @param [out]
* @return 成功返回元素下标 失败返回-1
*/
int search_by_data(datatype key,Seqlist *list)
{
//1.判断顺序表是否存在
//2.判断顺序表是否为空
if(NULL==list||empty(list))
{
return -1;
}
//3.按元素查找
for(int i=0;i<list->len;i++)
{
if(key==list->data[i])
{
return i;
}
}
return -1;
}
/*
* function: 按元素修改
* @param [ in]
* @param [out]
* @return 成功返回0 失败返回-1
*/
int update_by_data(datatype key,datatype e,Seqlist *list)
{
int sub=search_by_data(key,list);
if(sub==-1)
{
printf("update error\n");
}
list->data[sub]=e;
return 0;
}
/*
* function: 按元素插入
* @param [ in]
* @param [out]
* @return 成功返回0 失败返回-1
*/
int insert_by_data(datatype key,datatype e,Seqlist *list)
{
int sub=search_by_data(key,list);
if(sub==-1)
return -1;
insert_by_sub(list,sub,e);
return 0;
}
/*
* function: 按元素删除
* @param [ in]
* @param [out]
* @return 成功返回0 失败返回-1
*/
int delete_by_data(datatype key,Seqlist *list)
{
int sub=search_by_data(key,list);
if(sub==-1)
{
printf("delete error\n");
}
delete_by_sub(list,sub);
}
main.c
//写主函数
#include "head.h"
int main(int argc, const char *argv[])
{
Seqlist *list=create_list();
int n;
printf("please enter n:");
scanf("%d",&n);
datatype e;//表示插入的值
for(int i=0;i<n;i++)
{
printf("please enter rear element:");
scanf("%d",&e);
insert_rear(e,list);
}
output(list);
delete_rear(list);
output(list);
//按下标查找
int sub;
printf("please search sub:");
scanf("%d",&sub);
e=search_by_sub(sub,list);
if(e!=-1)
{
printf("search element is:%d\n",e);
}
//按下标修改
printf("please update sub:");
scanf("%d",&sub);
printf("please enter update element: ");
scanf("%d",&e);
update_by_sub(list,sub,e);
output(list);
//按下标插入
printf("please insert sub:");
scanf("%d",&sub);
printf("please enter insert element:");
scanf("%d",&e);
insert_by_sub(list,sub,e);
output(list);
//按下标删除
printf("please delete sub:");
scanf("%d",&sub);
delete_by_sub(list,sub);
output(list);
//按元素查找
datatype key;
printf("please enter search key:");
scanf("%d",&key);
int key_sub=search_by_data(key,list);
if(key_sub==-1)
puts("search error\n");
else
printf("find in %d\n",key_sub);
//按元素修改
printf("please enter update key:");
scanf("%d",&key);
printf("please enter update element: ");
scanf("%d",&e);
update_by_data(key,e,list);
output(list);
//按元素插入
printf("please enter insert key:");
scanf("%d",&key);
printf("please enter insert element:");
scanf("%d",&e);
insert_by_data(key,e,list);
output(list);
//按元素删除
printf("please enter delete key:");
scanf("%d",&key);
delete_by_data(key,list);
output(list);
return 0;
}