Solve the knapsack problem.

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But really, you are given a set of tiles (which all happen to be some subset of a 3x3) and a set of constraints–a MxN grid and how many of each tile to place. Count how many constraints are possible.

Tiles may be rotated and/or flipped.

Given a directed graph defined where aaa: you hhh means aaa is connected to you and hhh, how many paths are there from you to out.

Given a target light pattern [.##.] and a series of buttons ((3) (1, 3) etc) where the first button toggles light ‘3’ (the 4th light) and the second toggles the first and 4th etc, what is the minimum number of buttons you need to press to match the light pattern.

Given a list of points (2D), find the pair of points which form the largest rectangle.

Given a list of points in 3D space, connect the 1000 closest nodes to each other. Calculate the product of the size of the 3 largest resulting regions?

You are given a map like this:

.......S.......
...............
.......^.......
...............
......^.^......
...............

A laser shines from the top S and splits each time it hits a ^, making this:

.......S.......
.......|.......
......|^|......
......|.|......
.....|^|^|.....
.....|.|.|.....

The two lasers in the center of this example merge to count as one laser.

Count how many times lasers hit splitters.

Given input like this:

123 328  51 64 
 45 64  387 23 
  6 98  215 314
*   +   *   +  

Apply the operation in each column then sum the results.

Given a list of ranges (inclusive) and a list of IDs, how many of the IDs are in any range?

Given a grid of solid @ and empty cells ., count how many solid cells have less than 4 neighbors.

Given a list of numbers, for each find the two digits in the number which if concatenated make the largest. Sum these values.

For example: 811111111111119 should be 89.