# National Zoo

Itβs always a challenge to find where the animals are.

### Snake Pit

Place snakes and identify their heads such that:

- No snake orthogonally touches another snake of the same length
- Snakes are one-cell-wide paths that do not touch themselves, even diagonally
- The snakes have a head and a tail (there are no one-cell snakes)
- No snake head can share an edge with another snakeβs head or tail
- Numbers present indicate the length of the snake in that cell
- All cells are occupied by exactly one snake

#### Example and Solution

(emoji represent the heads of each snake)

4 | 4 | 6 | 4 | 4 | 4 | π | |||||

3 | 6 | 10 | 10 | π | 3 | ||||||

6 | 6 | 10 | 10 | 3 | |||||||

6 | 2 | π | 6 | π | 10 | 2 | |||||

10 | 10 | 10 | 10 | 10 | π |

4 | 4 | 6 | |||||||

6 | 6 | 4 | 7 | 6 | |||||

6 | 9 | 9 | 2 | ||||||

10 | 10 | 2 | 10 | ||||||

9 | 9 | 10 | 4 | 8 | |||||

7 | 10 | 10 | 10 | 4 | |||||

7 | 7 | 4 | 4 | ||||||

7 | 6 | 3 | 8 | ||||||

3 | 3 | 7 | 8 | 8 | |||||

2 | 4 | 4 |

### Penguin Floes

Identify ice floes such that:

- No floes share an edge
- Each floe has exactly one number, and the number of cells in the floe is equal to that number
- All water cells are edge-connected
- No 2x2 square of water cells is present

At the same time, place penguins such that:

- There is exactly one penguin on each ice floe
- Each penguin is on the cell of its floe whose 8 surrounding cells contain the longest continuous stretch of water

#### Example and Solution

4 | |||||||||||

1 | π§ | π§ | |||||||||

1 | π§ | ||||||||||

2 | π§ |

4 | 3 | ||||||||

8 | 6 | ||||||||

6 | |||||||||

5 | 4 | ||||||||

1 | |||||||||

7 | 3 |

### Fish Tanks

- Each region represents an aquarium that can be filled with water
- Within an aquarium, the water reaches a certain number of cells up from its bottommost cell(s)
- Shade cells to represent a water-filled cell, blank to represent an empty cell
- Numbers on the outside represent the number of shaded/water-filled cells

At the same time, place fish in the tanks such that:

- There are two fish in each aquarium, row, and column
- All fish are within the water

#### Example and Solution

4 | 2 | 4 | 2 | ||||||||

π | π | ||||||||||

π | π | ||||||||||

π | π | ||||||||||

π | π | ||||||||||

π | π |

4 | 4 | 6 | ||||||||

7 | ||||||||||

9 | ||||||||||

### Bat cave

- Shade some cells to leave behind an unshaded cave
- Numbers cannot be shaded
- The cave is edge-connected
- All shaded regions are edge-connected to the boundary
- The number indicates the cells visible from there (horizontally and vertically, including self)

At the same time, place bats in the cave such that:

- Each cell in the cave can be seen by at least one bat
- No bat can see another bat
- No bat occupies a number cell

#### Example and Solution

3 | 3 | π¦ | |||||||||

7 | 2 | 7 | π¦ | 2 | |||||||

3 | π¦ | 3 | |||||||||

2 | π¦ | 2 |

2 | 3 | 2 | |||||||

7 | 9 | 8 | 9 | ||||||

3 | |||||||||

3 | 5 | ||||||||

10 | 4 | 7 | |||||||

3 | 4 | 6 | |||||||

7 | 3 | ||||||||

6 | 3 | 10 | |||||||

2 | 5 |

π+π§

π+π¦

T | M | L | C | B | A | G | P | H | U |

A | T | E | E | H | S | U | G | C | H |

Y | E | R | E | E | O | E | A | F | G |

N | L | T | U | A | M | T | T | U | G |

U | R | L | W | B | S | I | C | T | E |

W | D | E | F | P | F | O | O | L | B |

F | E | F | S | I | A | U | W | R | A |

P | F | F | Y | H | M | R | S | L | A |

R | I | C | T | O | P | U | P | R | W |

I | O | C | C | P | S | E | U | Y | S |