Partition Equal Subset Sum: [1, 5, 11, 5], target 11
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T = some subset of the first i numbers sums to s
s =        0   1   2   3   4   5   6   7   8   9  10  11
none       T   .   .   .   .   .   .   .   .   .   .   .
+1         T   T   .   .   .   .   .   .   .   .   .   .
+5         T   T   .   .   .   T   T   .   .   .   .   .
+11        T   T   .   .   .   T   T   .   .   .   .   T
+5         T   T   .   .   .   T   T   .   .   .   T   T

[1, 5, 11, 5] -> true  (5 + 5 + 1 = 11 = 11)
[1, 2, 3, 5] -> false  (total 11 is odd)
[1, 2, 4] -> false  (total 7 is odd)