Pentomino Snakes (511)

Write numbers from 1 and 5 into some white cells to build sequences of orthogonally adjacent cells, containing all numbers in strictly increasing or decreasing order (number snakes). The number of the snakes will be given in a circle next to the puzzle. These number snakes must all be of identical shape, which can be rotated or reflected. No two number snakes can touch each other orthogonally, diagonal touch is allowed. Numbers in clue cells denote which number in a black cell (number cell) is the first number in the direction the arrow points to. A zero denotes that there is no number cell in the direction the arrow points to. No snake may see another snake. A snake's eyes are on the side of its head (the 1-cell) opposite the 2-cell. It can only see in that direction, in a straight line, up to the edge of the grid or the nearest black cell (whichever is closer).

Reference: WPC 2016 (65)