常用程式碼記錄
阿新 • • 發佈：2018-11-01
參考網路眾多資料，記錄下常用的功能。
一、IP合法性判斷
#include<iostream>
#include<string>
#include<vector>
#include<iterator>
#include<sstream>
using namespace std;
//注意：當字串為空時，也會返回一個空字串
void split(string& s, string& delim, vector<string>* ret)
{
size_t last = 0 二、去除字串2在字串1中所有字元
#include <iostream>
#include <string>
#include <vector>
#include <sstream>
#include <stdio.h>
#include <string.h>
#include <cstdlib>
using namespace std;
char * string_del_characters( char * const src, const char * const dest )
{
int destLen = strlen(dest);
int hashTable[256] = { 0 };
char * p = src;
int index = 0;
for( int i = 0; i < destLen; i++ )
{
hashTable[(int)dest[i]] = 1;
}
while( *p != '\0' )
{
if( 0 == hashTable[(int)*p] )
{
src[index++] = *p;
}
p++;
}
src[index] = '\0';
return src;
}
int main()
{
char src[1024];
char dest[1024];
scanf("%s",src);
scanf("%s",dest);
char * pResult = string_del_characters( src, dest );
std::cout << pResult << std::endl;
}三、根據中心座標找最近距離
#include <iostream>
#include <string>
#include <vector>
#include <sstream>
#include <cmath>
using namespace std;
int main() {
vector<int> sets;
string s;
getline(cin, s);
stringstream sstr(s);
string token;
//輸入字串，根據,號分割
while (getline(sstr, token, ',')) {
sets.push_back(atoi(token.c_str()));
}
int src_x = sets[0];
int src_y = sets[1];
int n = sets[2];
if (n == 0) {
cout << "(" << src_x << "," << src_y << ")" << endl;
return 0;
}
float minDistance = 128 * 2;
vector<int> npc(2 * n, 0);
for (int i = 0; i < 2 * n; ++i) {
npc[i] = sets[i + 3];
}
int index;
//求座標距離
for (int i = 0; i < 2 * n; i += 2) {
float distance = sqrtf(pow(npc[i] - src_x, 2) + pow(npc[i + 1] - src_y, 2));
if (distance < minDistance) {
minDistance = distance;
index = i;
}
}
cout << "(" << npc[index] << "," << npc[index + 1] << ")" << endl;
return 0;
}
四、根據前序遍歷和中序遍歷求後序
/*************************************************************************mZ
> Author: FengXin
> Mail: [email protected]
> Created Time: 2016年10月27日 星期四 20時01分43秒
************************************************************************/
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<math.h>
#include<sys/signal.h>
#include<unistd.h>
#include<sys/types.h>
#include<sys/wait.h>
#include<sys/stat.h>
#include<fcntl.h>
typedef struct node
{
char data; //結點資料
struct node *Lchild; //左孩子
struct node *Rchild; //右孩子
}tree; //樹的結點
int Lchild_len(char insequence[20],char root_data) //得到左孩子的長度
{
int len=strlen(insequence);
int i=0;
int sum=0; //記錄左孩子長度
while(insequence[i]!=root_data)
{
i++;
sum++;
}
return sum;
}
int Rchild_len(char insequence[20],char root_data) //得到右孩子的長度
{
int i=0;
int sum=0; //記錄右孩子長度
while(insequence[i]!='\0'&&insequence[i++]!=root_data);
while(insequence[i]!='\0')
{
sum++;
i++;
}
return sum;
}
tree* create_tree(char presequence[20],char insequence[20]) //建立二叉樹
{
tree* temp=(tree*)malloc(sizeof(tree)); //建立結點
int L_len,R_len; //儲存左右孩子長度
char L_presequence[20],L_insequece[20]; //建立左孩子時傳入的左孩子的前序串和中序串
char R_presequence[20],R_insequece[20]; //建立右孩子時傳入的右孩子的前序串和中序串
L_presequence[0]=L_insequece[0]=R_presequence[0]=R_insequece[0]='\0';
if(strlen(presequence)!=0&&strlen(insequence)!=0) //傳入的序列串非空
{
temp->data=presequence[0]; //根結點資料賦值
L_len=Lchild_len(insequence,presequence[0]); //獲得孩子的長度
R_len=Rchild_len(insequence,presequence[0]);
strncpy(L_presequence,presequence+1,L_len); //得到要遞迴建立孩子時要傳入的前序遍歷串和中序遍歷串
*(L_presequence+L_len)='\0'; //字串末尾加上'\0'
strncpy(R_presequence,presequence+L_len+1,R_len);
*(R_presequence+R_len)='\0';
strncpy(L_insequece,insequence,L_len);
*(L_insequece+L_len)='\0';
strncpy(R_insequece,insequence+L_len+1,R_len);
*(R_insequece+R_len)='\0';
temp->Lchild=create_tree(L_presequence,L_insequece); //遞迴建立左子樹
temp->Rchild=create_tree(R_presequence,R_insequece); //遞迴建立右子樹
return temp; //返回結點地址
}
else //若根結點無孩子，則返回空指標
{
return NULL;
}
}
void postorder(tree *root) //後序遍歷樹輸出
{
if(root!=NULL)
{
postorder(root->Lchild);
postorder(root->Rchild);
printf("%3c",root->data);
}
else
return;
}
int main()
{
char presequence[20]; //存先序序列
char insequence[20]; //存中序序列
tree *root;
printf("請輸入先序序列\n");
scanf("%s",presequence);
printf("請輸入中序序列\n");
scanf("%s",insequence);
root=create_tree(presequence,insequence);
printf("建立二叉樹成功\n");
printf("後序遍歷輸出為:\n");
postorder(root);
printf("\n");
}五、實現memcpy函式
#include <iostream>
#include <string>
#include <vector>
#include <sstream>
#include <stdio.h>
#include <string.h>
#include <cstdlib>
using namespace std;
char *my_memcpy(char *dst, const char* src, int cnt)
{
if(dst == NULL || src == NULL) return NULL;
char *ret = dst;
if (dst >= src && dst <= src+cnt-1) //記憶體重疊，從高地址開始複製
{
dst = dst+cnt-1;
src = src+cnt-1;
while (cnt--)
*dst-- = *src--;
}
else //正常情況，從低地址開始複製
{
while (cnt--)
*dst++ = *src++;
}
return ret;
}
char * str_copy(char *dst,const char *src)
{
if(dst == NULL || src == NULL) return NULL;
char *ret = dst;
my_memcpy(dst, src, strlen(src)+1);
return ret;
}
int main()
{
char src[1024];
char dest[1024];
scanf("%s",src);
// scanf("%s",dest);
char * pResult = str_copy(dest, src );
std::cout << pResult << std::endl;
}六、對學生的若干科成績進行排序
Alay 80 90
Bob 95 99 88
Cally 88 90
#include <iostream>
#include <sstream>
#include <cstdlib>
#include <vector>
#include <algorithm>
using namespace std;
//對學生的若干科成績進行排序
struct students{
string name;
int avg;
};
bool comp_as_int(students objA, students objB)
{
return (objA.avg>objB.avg);
}
int main() {
vector<students> vec;
students obj;
string inputstr;
while(getline(cin,inputstr))
{
//inputstr:i am a student
//cout<<inputstr<<endl;
istringstream iss;
iss.str(inputstr);
string tempstr;
//根據空格分割讀取string
int i=0;
double sum = 0;
while(iss>>tempstr)
{
if(i==0)
{
// cout<<tempstr<<endl;
obj.name = tempstr;
}
else
{
//cout<<atoi(tempstr.c_str())<<endl;
sum += atoi(tempstr.c_str());
}
i++;
}
double x = sum/(i-1);
//四捨五入取整
int avg = (int)(x+0.5)>(int)x?(int)x+1:(int)x;
obj.avg = avg;
vec.push_back(obj);
}
//stable_sort是穩定排序。
sort(vec.begin(), vec.end(), comp_as_int);
for (vector<students>::iterator it = vec.begin(); it != vec.end(); it++)
cout << (*it).name << " "<<(*it).avg<<endl;
cout << endl;
return 0;
}