C :

#include<stdio.h>
int main()
{
	long i=1,j=1,k=2,t;
	scanf("%ld",&t);
	while(--t)
	{
		if(k%2==0)
		{
			if(i==1)
			{
				j++;
				k++;
			}
			else
			{
				i--;
				j++;
			}
		}
		else
		{
			if(j==1)
			{
				i++;
				k++;
			}
			else
			{
				i++;
				j--;
			}
		}
	}
	printf("%ld/%ld\n",i,j);
	return 0;
}

C++ :

#include<cstdio>
int main()
{
  int n;
  while(scanf("%d",&n)==1)//如果存在输入 
  {
     int k=1,s=0;
     for(;;)
     {
       s+=k;
       if(s>=n)//所求项是第k条对角线的倒数第s-n个元素 
       {
         printf("%d/%d\n", s-n+1,k-s+n);
         break;        
       }       
       k++;
     }                        
  }    
  return 0;
}//数学知识，先分析,小手

Pascal :

var n,i,x,y,a:longint; 
begin
 readln(n); 
 x:=1;y:=1; 
 i:=1;a:=1; 
 while i<=n do
  begin
   inc(i); 
   if a=1 then begin inc(x);dec(y);end
   else begin inc(y);dec(x);end; 
   if x<=1 then begin a:=1; 
    if i<=n then begin inc(i);inc(y);end;end; 
   if y<=1 then begin a:=2; 
    if i<=n then begin inc(x);inc(i);end;end; 
  end; 
 writeln(x,'/',y); 
end.