[C language] PTA 7-91 output leap year

Output 21 All leap year years in the century ending in a certain year . Be careful ： The criterion of leap year is that the year can be 4 Divide but not be 100 to be divisible by 、 Or can be 400 to be divisible by .

Input format :

Enter... On one line 21 One of the closing years of the century .

Output format :

Output all leap years that meet the conditions line by line , That is, one line per year . Input if not 21 The year of the century is exported "Invalid year!". If there are no leap years , The output “None”.

sample input 1:

2048

No blank lines at the end

sample output 1:

2004
2008
2012
2016
2020
2024
2028
2032
2036
2040
2044
2048

No blank lines at the end

sample input 2:

2000

sample output 2:

Invalid year!

Ideas ： It starts with a branch statement ：1, Illegal input （ be not in 21 Within the scope of the century, it does not belong to 2001-2100）;2、 There is no leap year in the interval （ That is, the number of years entered is less than 2004）,3、 There are leap years in the interval

For the input with leap years in the interval , Use a loop to output all leap years . Here, each cycle directly makes i=i+4, Not divisible 100 Words （ In fact, it can divide 100 There is only 2100 year ） It's leap year .

#include<stdio.h>
int main(){
	int year;
	scanf("%d",&year);
	if( year<2001 || year>2100){
		printf("Invalid year!");
	}else if(year<2004){
        printf("None");
    }
    
    else{
		int i;
		for(i=2004;i<=year;i=i+4){
			if(i%100==0){
				continue;
			}
			
			if(year-i<4)
			{printf("%d",i);
			}
			else
			{printf("%d\n",i);
			}
		}
	}
	
	return 0;
}