day_3.py

# Advent of Code Day 3 solution - https://adventofcode.com/2019/day/3

# TEST INPUT - set 1 has closest 156 least steps 610, set 2 has closest 135 least steps 410

# wire_one_moves = "R75,D30,R83,U83,L12,D49,R71,U7,L72"
# wire_two_moves = "U62,R66,U55,R34,D71,R55,D58,R83"

# wire_one_moves = "R98,U47,R26,D63,R33,U87,L62,D20,R33,U53,R51"
# wire_two_moves = "U98,R91,D20,R16,D67,R40,U7,R15,U6,R7"

# ACTUAL INPUT

wire_one_moves = "R990,U944,L921,U993,L64,U29,R899,D406,R841,U716,L32,U658,L830,D481,L441,U491,L687,D847,L459,U920,R165,U224,L896,D868,L191,U877,L909,U467,R798,U132,R234,U49,R484,U911,R108,D308,R867,U350,L404,U107,L84,U668,R850,U470,L182,U93,R284,U999,L664,U110,R650,D189,R540,D112,R794,U999,R871,D829,L549,U988,R654,D411,R323,D774,R529,U275,L909,U936,R122,D922,L331,U813,L748,U770,R511,D892,L770,U318,R661,U823,R210,D393,L694,U929,L76,D619,R395,U651,R526,U145,R851,U112,R73,D89,R17,U929,R807,U87,R764,D158,L820,U803,L785,D205,L828,D271,L839,D482,L797,U338,R322,D633,L292,U16,R627,U19,R548,U516,L384,U83,R256,U937,R404,U322,R671,D543,L412,U446,R238,U246,L794,D750,L34,U317,L994,U874,L247,D20,R491,U834,L498,D987,R2,U175,R452,U168,R495,D183,R201,U532,L192,U984,L566,D471,L704,D2,L776,U5,R911,U308,R763,D555,R458,D439,L968,D78,R549,D583,R289,D355,L503,D871,L881,U516,L507,D551,R711,U702,L308,D905,L408,U932,L884,U218,L158,D562,L200,D114,R673,U448,R887,U181,R247,U329,L965,U495,L329,D162,L265,D389,R419,U435,R258,U146,R208,D184,R730,D19,L78,D886,R472,D350,R484,U392,L542,U601,L202,U974,L310,U52,L537,U597,L163,D655,R928,U269,L926,D790,L513,U441,L90,U581,L211,U871,R603,D130,L220,U459,L933,U648,R721,U642,R301,U537,L858,D777,R823,U14,R820,D218,L96,D318,L206,U280,R887,D241,L752,U828,R354,U864,R844,D872,L728,D298,L234,U695,R434,D94,R905,D592,L32,D860,R680,D197,R886,U760,L232,U916,L452,U248,R715,D773,R867,U77,R751,D36,R565,U897,R782,U931,R546,U261,R920,D296,R451,U258,L394,U965,R912,D593,L990"
wire_two_moves = "L994,U515,R163,U863,L343,U162,L875,D92,L483,D601,R79,D761,L389,U167,L145,U145,L247,U886,R61,U820,L584,D239,R402,U805,R956,U126,R615,D322,R431,D460,R397,D511,R805,D177,L778,U296,R599,U759,R40,U1,L422,U751,R94,U401,R504,U940,L564,U24,R595,U944,R815,U672,R787,D854,R579,D604,L62,U670,L516,U199,L639,D919,L485,U655,R391,U669,R772,D34,R868,D12,L108,U295,R701,D603,R493,U927,R29,D34,R499,U111,L87,U190,R884,D658,R474,D166,R921,U698,R592,U25,R710,D398,L26,U696,L432,D887,R469,U656,L428,D188,L543,D150,R160,U543,R743,U692,R618,D148,R956,U753,L175,D789,R897,U305,L137,D914,R330,D780,R744,D473,L754,U482,L975,D413,L698,U656,L177,U419,R13,D827,L67,D800,R369,U97,L34,D588,L41,D760,L164,U224,L921,D311,R489,U956,R277,U180,R724,U748,R785,U826,L426,D957,R303,U16,L729,U224,L712,U43,L280,D648,R987,D941,R154,D581,R876,U615,L480,D103,R636,D276,R948,U89,R434,D212,R837,D295,R532,D390,R374,D926,R911,D110,R258,U83,L955,U747,L925,D366,R571,U241,R628,D344,R919,U117,R337,D683,L720,U261,L124,D545,R979,D601,L906,D324,R441,U678,L978,U744,L472,D217,R799,U740,L77,U964,L278,U497,R441,U21,L37,U319,L24,D211,L44,U459,R35,D609,R900,D538,R397,D776,R629,D860,R519,D340,R168,U603,R46,U889,R897,D442,R997,U705,L82,D963,R941,U701,L347,D824,R269,U891,L569,D558,L867,U145,R121,D369,R542,U227,L198,U863,L755,U273,L734,D233,R578,U67,L821,U600,L203,D234,R695,U819,L639,D700,R295,D129,L612,U157,R212,U536,L968,U562,L999,D391,L231,U262,R334,D967,R463,U748,R842,D500,R860,U856,R263,D633,R460,D337,L880,U146,R910"

def wire_coords(moves):
    """Generate a list of x, y coords for each step of the wire along the grid."""
    splitmoves = moves.split(',')
    # prime coords list with starting point of 0, 0
    coords = [(0,0)]
    for move in splitmoves:
        direction = move[0]
        # if moving left or down we want to decrement the coord instead
        increment = -1 if direction in ('L', 'D') else 1
        distance = int(move[1:])
        # for each step of this move, add an updated x, y coordinate
        for n in range(distance):
            x, y = coords[-1]
            if direction in ('L', 'R'):
                x += increment
            elif direction in ('U', 'D'):
                y += increment
            coords.append((x, y))
    return coords

def find_best_intersections(wire_one_moves, wire_two_moves):
    """Find the target wire intersections."""
    wire_one_coords = wire_coords(wire_one_moves)
    wire_two_coords = wire_coords(wire_two_moves)
    intersections = [i for i in set(wire_one_coords).intersection(wire_two_coords) if i != (0,0)]
    # manhattan distance is just the sum of the absolute x and y coordinates for an intersection
    raw_closest = min([abs(x)+ abs(y) for x, y in intersections])
    # for least steps we can get the number of steps for each intersection by looking up the coord list index 
    # for that intersection. starting the list with (0,0) means that the 1st actual step is index 1.
    least_steps = min([wire_one_coords.index(i) + wire_two_coords.index(i) for i in intersections])
    print("Closest: ", raw_closest)
    print("Least steps: ", least_steps)

find_best_intersections(wire_one_moves, wire_two_moves)