杭电acm2133 今天星期几

#include<iostream>  #include<string.h>  using namespace std;  int a[13] = {0,31,29,31,30,31,30,31,31,30,31,30,31};  int b[13] = {0,31,28,31,30,31,30,31,31,30,31,30,31};  char s[8][10] = {"Sunday","Monday","Tuesday","Wednesday","Thursday","Friday","Saturday"};  bool IsRunNian(int year)  {      if((year%4==0 && year%100!=0) || year%400==0)          return true;      return false;  }  int main()  {      int year,month,day;      while(cin >> year >> month >> day)      {          if(IsRunNian(year))          {              if(day > a[month] || month == 0 || day == 0)              {                  cout << "illegal" << endl;                  continue;              }          }          else          {              if(day > b[month] || month == 0 || day == 0)              {                  cout << "illegal" << endl;                  continue;              }          }          int sum = 0;          for(int i = 1; i < year; ++i)          {              if(IsRunNian(i))                  sum += 366;              else                  sum += 365;              sum %= 7;          }          for(int i = 0; i < month; ++i)          {              if(IsRunNian(year))                  sum += a[i];              else                  sum += b[i];              sum %= 7;          }          sum += day;          sum %= 7;          cout << s[sum] << endl;      }      return 0;  }