code: static int[] join(int[] pathToY, int[] pathToZ) {
          int[] path = copyOf(pathToY, pathToY.length + pathToZ.length);
          int j = path.length - 1;
          for (int i = 0; i < pathToZ.length; i++) {
              path[j--] = pathToZ[i];
          }
          return path;
      }
docs: Join the two paths end on end and ignore the first vertex of the second
  path. {0, 1, 2} and {0, 3, 4} becomes {0, 1, 2, 4, 3}.
  
  @param pathToY first path
  @param pathToZ second path
  @return the paths joined end on end and the last vertex truncated