Code Appreciation--Sfeng Calculator

/*Title: The revolutionary contribution of the Sfeng calculator Sfeng speed algorithm is to predict rounding from a high.     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 the same, 2/7, 3/7, ...     6/7 are similar repeating decimal, multi-digit more than N/7, it is necessary to enter n the program simulates the Sfeng speed algorithm multiplied by 7 of the operation process.     The single-digit rule multiplied by 7 is: even times 2, odd times 2, plus 5, all take only one digit. The Carry rule multiplied by 7 is: Full 142857 ... Enter 1, full 285714 ... Enter 2, full 428571 ... Enter 3, full 571428 ... Enter 4, full 714285 ... Enter 5, full 857142 ... In 6*/#include<stdio.h>#include<string.h>//Calculate BitsintGe_wei (inta) {    ifA2==0)        returnA2) %Ten; Else        returnA2+5) %Ten; }//Calculate RoundingintJin_wei (Char*p) {    Char* level[] = {        "142857",        "285714",        "428571",        "571428",        "714285",        "857142"    }; Charbuf[7]; buf[6] =' /'; strncpy (Buf,p,6); inti;  for(i=5; i>=0; i--){        intR =strcmp (Level[i], buf); if(r<0)returni+1;  while(r==0) {p+=6; strncpy (Buf,p,6); R=strcmp (Level[i], buf); if(r<0)returni+1; if(r>0)returnI//Fill in        }    }        return 0;}//multiply multiple digits by 7voidFChar*s) {intHead =Jin_wei (s); if(Head >0) printf ("%d", head); Char* p =s;  while(*p) {        intA = (*p-'0'); intx = (Ge_wei (a) + Jin_wei (p+1)) %Ten; printf ("%d", x); P++; } printf ("\ n");}intMain () {f ("428571428571"); F ("34553834937543"); return 0;}

Code Appreciation--Sfeng Calculator