char *search( pat, text, n )
   char *pat, *text;
   int n;

   { int i, j, k, m, skip[MAXCHAR];

     m = strlen(pat);
     if( m==0 ) return( text );
     for( k=0; k<MAXCHAR; k++ ) skip[k] = m;
     for( k=0; k<m-1; k++ ) skip[pat[k]] = m-k-1;

     for( k=m-1; k < n; k += skip[text[k] & (MAXCHAR-1)] ) {
          for( j=m-1, i=k; j>=0 && text[i] == pat[j]; j-- ) i--;
          if( j == (-1) ) return( text+i+1 );
          }
     return( NULL );
   }