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  1. #include <stdio.h>
  2. #include <string.h>
  3. #include <time.h>
  4.  
  5. const char weekname[7][10] = {"日曜日","月曜日","火曜日","水曜日","木曜日","金曜日","土曜日"};
  6. const int table_mdays[2][12] = {{31,28,31,30,31,30,31,31,30,31,30,31},{31,29,31,30,31,30,31,31,30,31,30,31}};
  7. int isleap(int year){
  8.     return year % 4 == 0 && year % 100 != 0 || year % 400 == 0;
  9. }
  10. int mdays(int year, int month){
  11.     return table_mdays[isleap(year)][month-1];
  12. }
  13. int week_name2no(const char *str){
  14.     int i;
  15.     for(i = 0; i < 7; i++){
  16.         if(strcmp(str, weekname[i]) == 0){
  17.             break;
  18.         }
  19.     }
  20.     return i;
  21. }
  22.  
  23. int calc_day(int year, int month, int weeknum, int weekno){   
  24.     struct tm tm_in = {0,0,0,1,month-1,year-1900,0,0,0};
  25.     time_t t = mktime(&tm_in);
  26.     struct tm *tm_out = localtime(&t);    
  27.     int firstweekno = tm_out->tm_wday;
  28.     int day = (weekno - firstweekno + 7) % 7 + 1;
  29.     day += 7 * (weeknum-1);
  30.     if(day < 1 || day > mdays(year, month)){
  31.         day = -1;
  32.     }
  33.     return day;
  34. }
  35.  
  36. int main(void){
  37.     char buf[128] = {};
  38.     int year, month, weeknum, weekno, day;
  39.     char weekstr[10];
  40.     while(fgets(buf, 127, stdin) != NULL){
  41.         if(sscanf(buf, "%d-%d,第%d%[^\n]", &year, &month, &weeknum, weekstr) < 4){
  42.             puts("Invalid input.");
  43.             continue;
  44.         }
  45.         weekno = week_name2no(weekstr);
  46.         if(weekno >= 7){
  47.             puts("Invalid input.");
  48.             continue;
  49.         }
  50.         if(year < 1900 || month < 1 || month > 12){
  51.             puts("Invalid date.");
  52.             continue;
  53.         }
  54.         day = calc_day(year, month, weeknum, weekno);
  55.         if(day == -1){
  56.             puts("Invalid date.");
  57.         }else{
  58.             printf("%d-%02d-%02d\n", year, month, day);
  59.         }
  60.     }
  61.     return 0;
  62. }
  63.  
Success #stdin #stdout 0s 5660KB
comments (?)
stdin
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2021-07,第3月曜日
2021-07,第10月曜日
stdout
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2021-07-19
Invalid date.
https://ideone.com/t2aQ5O
19_983
language:
C (gcc 8.3)
created:
5 years ago
visibility:
public

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