PJWHash.c

#include<stdio.h>

/*Program to read a file and hash it using PJW hash*/

inline int inp()
{
    /*Fuction to improve input speed*/
    int noRead=0;
    char p=getchar_unlocked();
    for(;p<33;)
    {
     p=getchar_unlocked();
    };
    while(p>32)
    {
     noRead = (noRead << 3) + (noRead << 1) + (p - '0');
     p=getchar_unlocked();
    }
    return noRead;
};

int main()
{
    int n, a[10000], i;
    long long int h=0,g;
    FILE *fp;
    fp = fopen("/proc/stat","r");
    fscanf(fp,"%*s %d",&n);
    fclose(fp);
    n=n%10000;
    for (i=0;i<n;i++)
    {
        a[i]=inp();
        if(a[i]<0)
        a[i]=512+a[i];
    }
    /*PJW Hash function*/
    for(i=0;i<n;i++)
    {
         h = (h << 4) + a[i];               
         g = h & 0xf0000000;              
         if (g != 0)                     
             h = h ^ (g >> 24);            
         h = h ^ g;         
    }
    /*Written to hash file*/
    fp = fopen("hashed.txt", "a");                    
    fprintf(fp, "%lld\n", h);
}