有关C语言的程序问题，不会做。。。求大神帮忙！

Question

Task 2 Write a function to determine if the given year is a leap year. If it is, return 1, otherwise return 0.

Task 3 Write and test a function to print Floyd's triangle of n rows.
Number of rows of Floyd's triangle to print is entered by the user.
If n is 4, then the output should be as follows :
1
2 3
4 5 6
7 8 9 10

Task 4 Write and test a recursive C-function that calculates the series: 1+2+3+4+5+.........+N.

Task 5. Write and test the following recursive function that returns the nth square number:
long sqrFun(int n)
the square numbers are 0, 1, 4, 9, 16, 25, 36, ...
Note that s(n)=s(n-1)+2n-1 for n>1.

Task 6 Write and test a function which accepts any month-year and displays the calendar of the month.
For example, if the input is: 06-2014
then the output should be something like this:

JUNE, 2014
SUN MON TUE WED THU FRI SAT
1 2 3 4 5 6 7
8 9 10 11 12 13 14
15 16 17 18 19 20 21
22 23 24 25 26 27 28
29 30

Answer 1

//  闰年
int is_leap_year(unsigned int year)
{
int ret = 0;
if( ! (year%400))
{
  ret = 1;
}
else if(year%100)
{
ret = !(year%4);
}
return ret;
}

 

void Floyd_triangle(unsigned int row)
{
   int i,j;
   unsigned int num = 1;
   for( i = 0; i < row; i++)
   {
  for( j = i + 1; j; j--)
  {
  printf("%-5d",num++);
  }
  printf("\n");
   }
}

 

//递归计算1+2+3+4+5+.........+N.
unsigned recursive_calc (unsigned int num)
{
   if( num == 1)
   return num;

   return num+recursive_calc(num-1);

}

 

//returns the nth square number
   long sqrFun(int n)
   {
   if( n == 0 )
   {
   return 0;
   }
    

   return sqrFun(n-1)+2*n-1;
   }