回文日期

一、枚举回文串 再判断日期是否合法

#include<bits/stdc++.h>
using namespace std;
int monday[13] = { 0,31,28,31,30,31,30,31,31,30,31,30,31 };
//判断闰年
bool isyear(int year) {

    if (year % 400 == 0 || year % 100 != 0 && year % 4 == 0)
        return true;
    else return false;
}
bool judge(int date) {
    int year, mon, day;

    //在8为数字中取出年 月 日
    year = date / 10000;
    mon = (date%10000)/100;
    day = (date % 10000) % 100;

    //判断日期是否合法
    if (day == 0)
        return false;
    if (mon != 2 &&day > monday[mon])
        return false;
    if (mon < 1 || mon>12)
        return false;
    if (mon == 2) {
        if (isyear(year)) {
            if (day > monday[2] + 1)
                return false;
        }
        else if (day > monday[2])
            return false;

    }
    return true;
}
int main()
{
    int res = 0;
    int date1, date2;
    cin >> date1 >> date2;
    for (int i = 1000; i < 10000; i++) {
        int date = i, x = i;
        //用四位数字构造8位回文的方法
        for (int j = 0; j < 4; j++) {
            date = date * 10 + x % 10;
            x /= 10;
        }
        if (date >= date1 && date <= date2) {
            if (judge(date)) {
                res++;
            }
        }
    }
    cout << res << endl;
    return 0;
}

二、 自己暴力写的 TLE 只能过一半数据

#include<bits/stdc++.h>
using namespace std;
int ans=0;
bool isyear(int y){
    if(y%400==0||y%4==0&&y%100!=0)
        return true;
    else return false;
}
int get_huiwen(int num){
//     int year=0,mon=0,day=0;
//   for(int i=0;i<4;i++){
//       year=year*10+s[i]-'0';
//   }
//   for(int i=4;i<=5;i++){
//       mon=mon*10+s[i]-'0';
//   }
//   for(int i=6;i<=7;i++){
//       day=day*10+s[i]-'0';
//   }
  //cout<<year<<' '<<mon<<' '<<day<<endl;
  //int num=year*10000+mon*100+day;
  int temp=num;
  int sum=0;
  while(temp){
      int n=temp%10;
      sum=sum*10+n;
      temp/=10;
  }
  //cout<<num<<' '<<sum<<endl;
  if(num==sum)
    return 1;
  else return 0;
}
int m1[13]={0,31,29,31,30,31,30,31,31,30,31,30,31};
int m2[13]={0,31,28,31,30,31,30,31,31,30,31,30,31};
int main()
{

    string a,b;
    cin>>a>>b;
  int year1=0,mon1=0,day1=0,year2=0,mon2=0,day2=0;
 for(int i=0;i<4;i++){
      year1=year1*10+a[i]-'0';
  }
  for(int i=4;i<=5;i++){
      mon1=mon1*10+a[i]-'0';
  }
  for(int i=6;i<=7;i++){
      day1=day1*10+a[i]-'0';
  }


   for(int i=0;i<4;i++){
      year2=year2*10+b[i]-'0';
  }
  for(int i=4;i<=5;i++){
      mon2=mon2*10+b[i]-'0';
  }
  for(int i=6;i<=7;i++){
      day2=day2*10+b[i]-'0';
  }
  int num1=year1*10000+mon1*100+day1;
  int num2=year2*10000+mon2*100+day2;
  int nowy=year1,nowm=mon1,nowd=day1;
  int numnow=num1;
  while(numnow<=num2){
       if(get_huiwen(numnow)){
           ans++;
       }
      if(isyear(nowy)){
        if(nowm==2){
            if(nowd==29){
                nowd=1;
                nowm++;
            }
            else nowd++;
        }
        else if(nowm==1||nowm==3||nowm==5||nowm==7||nowm==8||nowm==10||nowm==12){

            if(nowd==31){
                nowd=1;
                nowm++;

            }
            else nowd++;
        }
        else if(nowm==4||nowm==6||nowm==9||nowm==11){
            if(nowd==30){
                nowd=1;
                nowm++;
            }
        }


      }
      else{
           if(nowm==2){
            if(nowd==29){
                nowd=1;
                nowm++;
            }
            else nowd++;
        }
        else if(nowm==1||nowm==3||nowm==5||nowm==7||nowm==8||nowm==10||nowm==12){

            if(nowd==31){
                nowd=1;
                nowm++;

            }
            else nowd++;
        }
        else if(nowm==4||nowm==6||nowm==9||nowm==11){
            if(nowd==30){
                nowd=1;
                nowm++;
            }
        }

    }
    numnow=nowy*10000+nowm*100+nowd;
  }
    cout<<ans<<endl;
    return 0;
}