第一次面试，有点紧张，犯了许多错误，电面就挂了。回头题目自己写下。不知道对不对。
题目：排序100个IP地址，其中可能有非法的IP（例如：192.168.2.1.11 ，192.256.7.1，192.010.2.1）
#include<iostream>
#include<sstream>
#include<string>
#include<vector>
#include<algorithm>
using namespace std;
//s1<s2 true. s1>=s2 false
bool myCmp(string s1, string s2){
if(s1 == s2)
return false; //
stringstream ss;
string w1, w2;
ss << s1;
getline(ss, w1, '.');
ss >> s1;
ss.str("");
ss.clear();
ss << s2;
getline(ss, w2, '.');
ss >> s2;
int i1 = atoi(w1.c_str());
int i2 = atoi(w2.c_str());
if(i1 != i2)
return i1 < i2;
//else w1==w2, recure
return myCmp(s1, s2);
}
bool check(string s){
int n = s.size();
//smallest 0.0.0.0 biggest 255.255.255.255
if(n > 15 || n < 7)
return false;
stringstream ss;
ss << s;
int part = 0;
while(getline(ss, s, '.')){
part++;
int i = atoi(s.c_str());
//more than 4 parts, out of[0,255], has 0xx string
if(part > 4 || i < 0 || i > 255 || s.size() > 1 && s[0] == '0')
return false;
}
//less than 4 parts
return part == 4;
}
void sortIP(vector<string> &IPs){
//check valid, move invalid ip to the end
vector<string>::iterator r = IPs.end() - 1;
vector<string>::iterator l = IPs.begin();
while(l <= r){
if(check(*l))
l++;
else{
swap(*l, *r);//*l = *r;
r--;
}
}//if all ip are invalid r=-1
//sort valid ip [begin(), r + 1)
sort(IPs.begin(), r + 1, myCmp);
}
int main(){
vector<string> IPs;
IPs.push_back("123.4.245.23");
IPs.push_back("104.244.253.29");
IPs.push_back("255.255.255.255");
IPs.push_back("255.255.255.257");
IPs.push_back("1.198.3.93");
IPs.push_back("32.183.93.40");
IPs.push_back("104.30.244.2");
IPs.push_back("104.244.4.101");
IPs.push_back("1.0.0.1");
IPs.push_back("1.0.0.0");
IPs.push_back("01.0.0.0");
IPs.push_back("255.192.255");
IPs.push_back("00.0.0.0");
IPs.push_back("0.1.0.0");
IPs.push_back("0.1.0.0.0");
IPs.push_back("104.244.4.29");
sortIP(IPs);
for(int i = 0; i < IPs.size(); ++i)
cout << IPs[i] << endl;
system("pause");
}