Hungarian algorithm

combinatorial optimization algorithm for the assignment problem

The Hungarian algorithm produces the best distribution, with for example: lowest price or shortest time.

Best distribution

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Example:

Driver Electrician Gardener Manager
Alex $8 $9 $98 $23
Ben $11 $69 $5 $86
Chris $20 $21 $7 $30
Dave $47 $7 $19 $62

Lowest price:

  • $23: Alex - manager
  • $11: Ben - driver
  • $7: Chris - gardener.
  • $7: Dave - electrician.

$48: Total

The Hungarian Matrix plays with values until the best distribution has only zeroes.

Step 1, zero in every line left to right

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Decrease each left to right line with its lowest value.

  • first line: - 8
  • second line: -5
  • third line: -7
  • fourth line: -7.
0 1 90 15
6 64 0 81
13 14 0 23
40 0 12 55

Step 2, zero in every top down line

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Decrease each top down line with its lowest value, - 15 for last one only.

0 1 90 0
6 64 0 66
13 14 0 8
40 0 12 40

Step 3, mark zeroes to keep

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Cover all zeroes with the lowest possible number of lines.

0 1 90 0
6 64 0 66
13 14 0 8
40 0 12 40

Find the lowest unmarked value: 6.

Step 4, make more zeroes

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Increase all values in marked lines with the value from step 3.

6 7 102 6
6 64 6 66
13 14 6 8
46 6 24 46

Decrease all values with the value from step 3.

0 1 96 0
0 58 0 60
7 8 0 2
40 0 18 40

Do steps 3 and 4 again and again, until you have enough zeroes.

Other websites

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