part1 (2527B)
1--- Day 12: Rain Risk --- 2 3Your ferry made decent progress toward the island, but the storm came in faster than anyone 4expected. The ferry needs to take [1m[37mevasive actions[0m! 5 6Unfortunately, the ship's navigation computer seems to be malfunctioning; rather than giving a route 7directly to safety, it produced extremely circuitous instructions. When the captain uses the PA 8system to ask if anyone can help, you quickly volunteer. 9 10The navigation instructions (your puzzle input) consists of a sequence of single-character 11[1m[37mactions[0m paired with integer input [1m[37mvalues[0m. After staring at them for a few 12minutes, you work out what they probably mean: 13 14 15 - Action [1m[37mN[0m means to move [1m[37mnorth[0m by the given value. 16 - Action [1m[37mS[0m means to move [1m[37msouth[0m by the given value. 17 - Action [1m[37mE[0m means to move [1m[37meast[0m by the given value. 18 - Action [1m[37mW[0m means to move [1m[37mwest[0m by the given value. 19 - Action [1m[37mL[0m means to turn [1m[37mleft[0m the given number of degrees. 20 - Action [1m[37mR[0m means to turn [1m[37mright[0m the given number of degrees. 21 - Action [1m[37mF[0m means to move [1m[37mforward[0m by the given value in the direction the 22ship is currently facing. 23 24 25The ship starts by facing [1m[37meast[0m. Only the L and R actions change the direction the ship 26is facing. (That is, if the ship is facing east and the next instruction is N10, the ship would move 27north 10 units, but would still move east if the following action were F.) 28 29For example: 30 31F10 32N3 33F7 34R90 35F11 36 37These instructions would be handled as follows: 38 39 40 - F10 would move the ship 10 units east (because the ship starts by facing east) to [1m[37meast 4110, north 0[0m. 42 - N3 would move the ship 3 units north to [1m[37meast 10, north 3[0m. 43 - F7 would move the ship another 7 units east (because the ship is still facing east) to 44[1m[37meast 17, north 3[0m. 45 - R90 would cause the ship to turn right by 90 degrees and face [1m[37msouth[0m; it remains at 46[1m[37meast 17, north 3[0m. 47 - F11 would move the ship 11 units south to [1m[37meast 17, south 8[0m. 48 49 50At the end of these instructions, the ship's Manhattan distance (sum of the absolute values of its 51east/west position and its north/south position) from its starting position is 17 + 8 = 52[1m[37m25[0m. 53 54Figure out where the navigation instructions lead. [1m[37mWhat is the Manhattan distance between 55that location and the ship's starting position?[0m 56 57