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July 2024 - Solution

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July 2024 Challenge


July 2024 Solution:

This is a search problem with a very large search space, so solutions can impose further restrictions which guide the search towards an optimal solution, in the case one exists. Computing the number of adjacent values inside the tiles themselves gives an intrinstic "cost" to using a tile, even when its connection to its neighbrors is only "01" and "10". For example, the cost of
 

0010 

0101 

1010 

1101 

Is 4. Ordering all tiles by their cost and summing the costs yields a minimum of 66 and 184 for both problems. Luckily, both values are achievable. For one to obtain the 66, 184 solutions, two additional constraints are added to the problem:

1. One must use only the small-cost tiles (e.g. tiles with a cost of 8 or 10 are discarded)
2. Two adjacent tiles must not have a "00" or "11" connection.
This makes the 66 problem solvable quickly using backtracking, while the 184 problems remains more challanging. A solution with value 66:
 

1101001010010101 

0010110101101011 

1010101010010100 

0101010101101001 

1010101010010110 

0110110101101001 

1001001010101010 

0101010101010101 

1010101010101010 

0101010101101001 

1010101010010101 

1010100101101010 

0101011010010101 

1010110101101010 

0101001010110101 

0011010101001010 

A solution with value 184:
 

10101101011010010101 

01010010101101101101 

01010101010101010010 

10101001001010101100 

01010110110101010011 

10010110100101010010 

00101001001010101101 

11010110110010101010 

00101001001101010101 

11010110110100110010 

10101001011011001101 

01101001001010101100 

10010110110101010011 

10101010101010101101 

01010101010010010010 

10010110100101101010 

01101001011010010101 

00110010101100110110 

11001100110011001011 

01101101010010010100