April 2020 - Solution
We were seeking the answer of Day 19, where writing PT (Ponder This):
01110111 10110010 11010010 11101000 00010100 10001000 11100010 10000000
gives a solution of 0.7000146451.
However, we've also accepted solutions that give ~70.007% after 10 days, such as:
01101010 10000001 10010010 00101001 10010100 00001010 10100101 01010010
Benjamin Lui found a 69.995% solution with only seven vertices:
0111000 1011110 1100100 1100100 0111011 0100101 0000110
Alper Halbutogullari was the first to find a solution that after 19 steps gets to ~70.0000865%:
01101010 10000001 10010010 00101001 10010100 00001010 10100101 01010010
Florian Fischer sent us a drawing (thanks)
Haye Chan found the best approximation (69.999981%) for seven cities and 28 days:
0000100 0001111 0000111 0100110 1111000 0111000 0110000
and Arthur Vause found a solution of 70.000002195% for 9 cities and 34 days:
000000010 000010101 000101101 001001100 010000011 001100010 011100001 100011000 011010100
Thanks to Alok Menghrajani for his writeup.