Va 10692-Huge Mod (exponential cycle)

#include <stdio.h>   #include <string.h>   #include <math.h>   #define LL long long     LL a[20];    LL euler(LL n)  {      LL m=(LL)sqrt(n+0.5);      LL ans=n;      for(LL i=2;i<=m;i++)      if(n%i==0){          ans=ans/i*(i-1);          while(n%i==0)n/=i;      }      if(n>1)ans=ans/n*(n-1);      return ans;  }    LL pmod(LL a,LL n,LL m)  {      LL now = 1;      for(LL i=0;i<n;i++) {          now *= a;          if(now>=m)  break;      }      if(now >= m)   now = m;      else now=0;        if(n==0)return 1;      LL x=pmod(a,n/2,m);      LL ans=(LL)x*x%m;      if(n%2==1) ans=ans*a%m;      return ans+now;  }    LL solve(LL cur,LL n,LL m)  {      if(cur==n-1)      {          if(a[cur]>=m)          return a[cur]%m+m;          else          return a[cur];      }      LL M=euler(m);      LL p=solve(cur+1,n,M);      LL ans=pmod(a[cur],p,m);      return ans;  }    int main()  {      char s[10];      LL m,n;      int cas=0;      while(scanf("%s",s)==1)      {          int l=strlen(s);          if(s[0]=='#'&&l==1)break;          m=0;          for(int i=0;i<l;i++)              m=m*10+s[i]-'0';          scanf("%lld",&n);          for(int i=0;i<n;i++)              scanf("%lld",&a[i]);          printf("Case #%d: %lld\n",++cas,solve(0,n,m)%m);      }      return 0;  }  #include <stdio.h>#include <string.h>#include <math.h>#define LL long longLL a[20];LL euler(LL n){    LL m=(LL)sqrt(n+0.5);    LL ans=n;    for(LL i=2;i<=m;i++)    if(n%i==0){        ans=ans/i*(i-1);        while(n%i==0)n/=i;    }    if(n>1)ans=ans/n*(n-1);    return ans;}LL pmod(LL a,LL n,LL m){    LL now = 1;    for(LL i=0;i<n;i++) {        now *= a;        if(now>=m)  break;    }    if(now >= m)   now = m;    else now=0;    if(n==0)return 1;    LL x=pmod(a,n/2,m);    LL ans=(LL)x*x%m;    if(n%2==1) ans=ans*a%m;    return ans+now;}LL solve(LL cur,LL n,LL m){    if(cur==n-1)    {        if(a[cur]>=m)        return a[cur]%m+m;        else        return a[cur];    }    LL M=euler(m);    LL p=solve(cur+1,n,M);    LL ans=pmod(a[cur],p,m);    return ans;}int main(){    char s[10];    LL m,n;    int cas=0;    while(scanf("%s",s)==1)    {        int l=strlen(s);        if(s[0]=='#'&&l==1)break;        m=0;        for(int i=0;i<l;i++)            m=m*10+s[i]-'0';        scanf("%lld",&n);        for(int i=0;i<n;i++)            scanf("%lld",&a[i]);        printf("Case #%d: %lld\n",++cas,solve(0,n,m)%m);    }    return 0;}