Instant Insanity

Given the nets of 4 cubes with the faces coloured in 4 colours, build a tower so that on each vertical wall no colour is repeated, that is all 4 colours appear.

Magic Caterpillars

Label the joints and legs of these graph theory caterpillars so that the vertex sums are all equal.

Plum Tree

Label this plum tree graph to make it totally magic!

Rainstorm Sudoku

Stage: 4 Challenge Level:

Invented by Henry Kwok

Rules of Rainstorm Sudoku

The variant is given such a name because of the many diagonal colour regions slanting in one direction, like heavy rainfall.

As in a standard Sudoku, the object of the puzzle is to fill in the whole 9x9 grid with numbers 1 through 9 so that each row, each column, and each of the nine 3x3 boxes must contain all the nine different numbers 1 through 9.

In addition, each diagonal colour region must be filled with the same number. Note that regions in the same colour on different parts of the grid do not necessarily contain the same number as each other.