1229. 日期问题（超级字符串处理+unique用法）

题目链接：

https://www.acwing.com/problem/content/1231/

题解：

估计自己太弱了，处理字符串比较痛苦，最后记得用unique去重。

代码：

#include <cstring>
#include <cstdio>
#include <string>
#include <iostream>
#include <algorithm>
#include <sstream>

using namespace std;

int months[] = {0,31,28,31,30,31,30,31,31,30,31,30,31};

bool check(int year,int mm,int dd){
    if(mm < 1 || mm > 12) return false;
    if( (mm != 2 && dd > months[mm]) || dd < 1) return false;
    if(mm == 2){
        int lamp = (year % 100 && year % 4 == 0) || year % 400 == 0;
        if(dd > months[mm] + lamp || dd < 1) return false;
    }
    return true;
}

const int N = 8;

int len = 0;
string ss[N]; 

int main(){
    string s;
    cin >> s;
    
    int n1 = (s[0]-'0')*10+(s[1]-'0');
    int n2 = (s[3]-'0')*10+(s[4]-'0');
    int n3 = (s[6]-'0')*10+(s[7]-'0');
    
    // cout << n1 << " " << n2 << " " << n3 << endl;
    if(n1 <= 59){
        int year = 20*100+n1;
        if(check(year,n2,n3)){
            stringstream strss;
            string mm = to_string(n2);
            if(n2 < 10) mm = "0" + mm;
            string dd = to_string(n3);
            if(n3 < 10) dd = "0" + dd;
            string yyyy = to_string(year);
            strss << year << "-" << mm << "-" << dd;
            string res = strss.str();
            ss[len] = res;
            len++;
        }
    }else{
        int year = 19*100+n1;
        if(check(year,n2,n3)){
            stringstream strss;
            string mm = to_string(n2);
            if(n2 < 10) mm = "0" + mm;
            string dd = to_string(n3);
            if(n3 < 10) dd = "0" + dd;
            string yyyy = to_string(year);
            strss << year << "-" << mm << "-" << dd;
            string res = strss.str();
            ss[len] = res;
            len++;
        }
    }
    
    if(n3 <= 59){
        int year = 20*100+n3;
        if(check(year,n1,n2)){
            stringstream strss;
            string mm = to_string(n1);
            if(n1 < 10) mm = "0" + mm;
            string dd = to_string(n2);
            if(n2 < 10) dd = "0" + dd;
            string yyyy = to_string(year);
            strss << year << "-" << mm << "-" << dd;
            string res = strss.str();
            ss[len] = res;
            len++;
        }
        if(check(year,n2,n1)){
            stringstream strss;
            string mm = to_string(n2);
            if(n2 < 10) mm = "0" + mm;
            string dd = to_string(n1);
            if(n1 < 10) dd = "0" + dd;
            string yyyy = to_string(year);
            strss << year << "-" << mm << "-" << dd;
            string res = strss.str();
            ss[len] = res;
            len++;
        }
        
    }else{
        int year = 19*100+n3;
        if(check(year,n1,n2)){
            stringstream strss;
            string mm = to_string(n1);
            if(n1 < 10) mm = "0" + mm;
            string dd = to_string(n2);
            if(n2 < 10) dd = "0" + dd;
            string yyyy = to_string(year);
            strss << year << "-" << mm << "-" << dd;
            string res = strss.str();
            ss[len] = res;
            len++;
        }
        if(check(year,n2,n1)){
            stringstream strss;
            string mm = to_string(n2);
            if(n2 < 10) mm = "0" + mm;
            string dd = to_string(n1);
            if(n1 < 10) dd = "0" + dd;
            string yyyy = to_string(year);
            strss << year << "-" << mm << "-" << dd;
            string res = strss.str();
            ss[len] = res;
            len++;
        }
    }
    sort(ss,ss+len);
    
    len = unique(ss,ss+len) - ss;
    // cout << len << endl;
    for(int i=0;i<len;i++) cout << ss[i] << endl; 
    
}