2014 The fifth session of the Blue Bridge Cup test-C + + program Design Group B-Sfeng Calculator

Title Description

The revolutionary contribution of the Sfeng speed algorithm is to predict rounding from a high position. Do not need 99 tables, completely subvert the traditional hand count!

The core foundation of the calculator is the multiplication of 1-bit numbers multiplied by multiple digits.

Where multiplying by 7 is the most complex, take it for example.

Because, 1/7 is a repeating decimal: 0.142857 ..., if the number of digits more than 142857 ..., will go 1

Similarly, 2/7, 3/7, ... 6/7 are similar repeating decimal, multi-digit more than N/7, will enter n

The following program simulates the process of multiplying the Sfeng speed algorithm by 7.

The single-digit rule multiplied by 7 is: even times 2, odd times 2, plus 5, all take only one digit.

The rounding rule multiplied by 7 is:
Full 142857 ... In 1,
Full 285714 ... In 2,
Full 428571 ... In 3,
Full 571428 ... In 4,
Full 714285 ... In 5,
Full 857142 ... In 6

Please analyze the program flow and fill in the missing code for the underlined part.

Program code:

　　

#include <stdio.h>
#include <stdlib.h>

Calculate Bits
int Ge_wei (int a)
{
if (a% 2 = = 0)
Return (A * 2)% 10;
Else
Return (A * 2 + 5)% 10;
}

Calculate rounding
int Jin_wei (char* p)
{
char* level[] = {
"142857",
"285714",
"428571",
"571428",
"714285",
"857142"
};

Char buf[7];
BUF[6] = ' + ';
strncpy (buf,p,6);

int i;
for (i=5; i>=0; i--) {
int r = strcmp (Level[i], buf);
if (r<0) return i+1;
while (r==0) {
p + = 6;
strncpy (buf,p,6);
R = strcmp (Level[i], buf);
if (r<0) return i+1;
　　　　　　if (r>0) return i; Blanks
}
}

return 0;
}

Multiply multiple digits by 7
void F (char* s)
{
int head = Jin_wei (s);
if (Head > 0) printf ("%d", head);

char* p = s;
while (*p) {
int a = (*p-' 0 ');
int x = (Ge_wei (a) + Jin_wei (p+1))% 10;
printf ("%d", x);
p++;
}

printf ("\ n");
}

int main ()
{
F ("428571428571");
F ("34553834937543");
return 0;
}

2014 The fifth session of the Blue Bridge Cup test-C + + program Design Group B-Sfeng Calculator