High precision, big integer power modulo

Format:

Cha ^ CHB % C

Both Cha and CHB are strings.

/** Fzu1759.cpp ** created on: 2011-10-11 * Author: bjfuwangzhu */# include <stdio. h> # include <string. h> # include <math. h> # include <stdlib. h> # define ll long # define nnum 1000005 # define Nmax limit 25int flag [Nmax], prime [Nmax]; int Plen; void mkprime () {int I, J; memset (flag,-1, sizeof (FLAG); for (I = 2, Plen = 0; I <Nmax; I ++) {If (flag [I]) {Prime [Plen ++] = I ;}for (j = 0; (j <Plen) & (I * prim E [J] <Nmax); j ++) {flag [I * prime [J] = 0; if (I % prime [J] = 0) {break ;}}} int getphi (int n) {int I, Te, Phi; Te = (INT) SQRT (N * 1.0); for (I = 0, phi = N; (I <Plen) & (prime [I] <= tE); I ++) {If (N % prime [I] = 0) {Phi = PHI/prime [I] * (Prime [I]-1); While (N % prime [I] = 0) {n/= prime [I] ;}}if (n> 1) {Phi = PHI/N * (N-1);} return Phi ;} int cmpbignum (int p, char * Ch) {Int I, Len; ll res; Len = strlen (CH); for (I = 0, Res = 0; I <Len; I ++) {res = (RES * 10 + (CH [I]-'0'); If (RES> P) {return 1 ;}} return 0 ;} int getmodbignum (int p, char * Ch) {int I, Len; ll res; Len = strlen (CH); for (I = 0, Res = 0; I <Len; I ++) {res = (RES * 10 + (CH [I]-'0') % P;} return (INT) RES;} int modular_exp (int, int B, int c) {ll res, temp; Res = 1% C, temp = A % C; While (B) {If (B & 1) {res = res * temp % C;} temp = temp * temp % C; B >>= 1 ;} return (INT) res;} void solve (int A, int C, char * Ch) {int Phi, res, B; Phi = getphi (c); If (cmpbignum (PHI, CH )) {B = getmodbignum (PHI, CH) + Phi;} else {B = atoi (CH);} res = modular_exp (A, B, C ); printf ("% d \ n", Res);} int main () {# ifndef online_judge freopen ("data. in "," r ", stdin); # endif int A, C; char Cha [nnum ], ChB [nnum]; mkprime (); While (~ Scanf ("% S % d", cha, CHB, & C) {A = getmodbignum (C, CHA); solve (A, C, CHB );} return 0 ;}