365. Water and Jug Problem

    /*
     *365. Water and Jug Problem
     *2016-7-15 by Mingyang 
     */
     public boolean canMeasureWater(int x, int y, int z) {
            return z == 0 || (long)x + y >= z && z % gcd(x, y) == 0;
          }
          public int gcd(int x, int y) {
            return y == 0 ? x : gcd(y, x % y);
          }