[Java] Zeller's Congruence Implementation, finds Day of Week given numeric month, day of month, and full year.

Zeller's Congruence

/************************************************
  * An implementation of Zeller's Congruence - presuming MM/DD/YYYY input
  * more information here: 
  * http://en.wikipedia.org/wiki/Zeller's_congruence
  * 
  * TL;DR notes: 
  *   - january and february are treated as months 13 & 14 of the previous year
  *   - resulting day number begins on saturday (0 = "Sat", 1 = "Sun", ... , 6 = "Fri")
  *   - actual formula listed below
  * ********************************************/

private void zeller (int mon, int day, int yr) {
    private String days[] = { "Saturday", "Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday" };
    int cenYr = yr % 100;
    int cen = yr / 100;
    
    if (mon <= 2) {
      yr -= 1;
      mon += 12;
    }
    
    /****************************************
      * ALGORITHM: 
      *   weekDay = (day + [13(month + 1)/5] + year of century + [year of century/4] + [century/4] - [2*century]) MOD 7
      * ************************************/
    
    int weekDay = (day + ( ( 13*(mon+1) )/5 ) + cenYr + (cenYr/4) + (cen/4) - (2*cen) );
    weekDay %= 7;

    return days[weekDay]; 
  }