Find the largest F (n) = N in a range, where F (n) is the sum of "1" in the calculation of a value less than or equal to n.

# include
using namespace STD;
pair mypair;
int count_1 (int n) // count the number of values containing "1"
{< br> int sum = 0;
while (n! = 0)
{< br> If (N % 10 = 1)
{< br> sum ++;
}< br> N/= 10;
}< br> return sum;

}
Int F (int n) // the sum of all the values in n that contain "1"
{
Int sum = 0;
While (N)
{
Sum + = count_1 (N );
N --;
}
Return sum;
}
Int main ()
{
Int maxcount = 0;
Int COUNT = 0;
Int Index = 0;
For (INT I = 1; I <4000000000; I ++) // find the largest F (n) = N
{
Count = f (I );
If (COUNT = I)
If (count> maxcount)
{
Maxcount = count;
Index = I;
}
}
If (maxcount = 0 & Index = 0)
Cout <"not met ";
Else
{
Mypair = make_pair (maxcount, index );
Cout <"the maximum number of 1 displayed is" <mypair. First <"this value appears in" <mypair. Second <Endl;
}
Return 0;
 

}