Solve day 15

15_goblins.py

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+#!/usr/bin/env python3
+import sys
+from operator import attrgetter
+from collections import defaultdict
+
+SPACE, WALL = 0, 1
+
+class BattleLost(Exception):
+    def __init__(self, team):
+        self.team = team
+
+class Unit:
+    counts = defaultdict(int)
+
+    def __init__(self, pos, team, ap):
+        self.pos = pos
+        self.team = team
+        self.hp = 200
+        self.ap = ap
+        self.counts[team] += 1
+
+    def neighbouring_enemies(self):
+        for nb in (self.pos - w, self.pos - 1, self.pos + 1, self.pos + w):
+            u = grid[nb]
+            if u not in (SPACE, WALL) and u.team != self.team and u.hp > 0:
+                yield u
+
+    def hit(self, ap):
+        self.hp -= ap
+        if self.hp <= 0:
+            grid[self.pos] = SPACE
+
+            self.counts[self.team] -= 1
+            if self.counts[self.team] == 0:
+                raise BattleLost(self.team)
+
+    def fight(self):
+        enemies = list(self.neighbouring_enemies())
+        if enemies:
+            min(enemies, key=attrgetter('hp', 'pos')).hit(self.ap)
+        return len(enemies) > 0
+
+    def move(self):
+        step = self.step_to_nearest_enemy()
+        if step is None:
+            return False
+        grid[self.pos] = SPACE
+        grid[step] = self
+        self.pos = step
+        return True
+
+    def step_to_nearest_enemy(self):
+        source = self.pos
+        Q = set(i for i, cell in enumerate(grid) if cell == SPACE)
+        Q.add(source)
+        size = max(Q) + 1
+        inf = len(grid) + 1
+        dist = [inf] * size
+        dist[source] = 0
+        prev = [None] * size
+
+        while Q:
+            u = min(Q, key=lambda x: (dist[x], x))
+            Q.remove(u)
+            for v in (u - w, u - 1, u + 1, u + w):
+                if v in Q:
+                    alt = dist[u] + 1
+                    if alt < dist[v]:
+                        dist[v] = alt
+                        prev[v] = u
+
+        def adjacent_enemies(v):
+            if dist[v] < inf and grid[v] == SPACE:
+                for nb in (v - w, v - 1, v + 1, v + w):
+                    u = grid[nb]
+                    if u not in (WALL, SPACE) and u.team != self.team and u.hp > 0:
+                        yield u
+
+        shortest = {}
+        for v, d in enumerate(dist):
+            for u in adjacent_enemies(v):
+                step = v
+                pathlen = 1
+                while prev[step] != source:
+                    step = prev[step]
+                    pathlen += 1
+                entry = pathlen, v, step
+                if u not in shortest or entry < shortest[u]:
+                    shortest[u] = entry
+
+        if len(shortest):
+            return min(shortest.values())[-1]
+
+def parse(f):
+    grid = []
+    w = 0
+    for y, line in enumerate(f):
+        for x, c in enumerate(line.rstrip()):
+            if c == '#':
+                grid.append(WALL)
+            elif c in '.':
+                grid.append(SPACE)
+            else:
+                grid.append(Unit(y * w + x, c, 3))
+        w = x + 1
+    return grid, w
+
+def show():
+    def red(text):
+        return '\x1b[31m' + text + '\x1b[0m'
+    def green(text):
+        return '\x1b[32m' + text + '\x1b[0m'
+
+    h = len(grid) // w
+    for y in range(h):
+        line = ''
+        hps = []
+        for x in range(w):
+            cell = grid[y * w + x]
+            if cell not in (WALL, SPACE):
+                color = red if cell.team == 'G' else green
+                t = color(cell.team)
+                hps.append('%s(%d)' % (t, cell.hp))
+                line += t
+            else:
+                line += '#' if cell == WALL else ' '
+        if hps:
+            line += '   ' + ', '.join(hps)
+        print(line)
+
+def simulate(ap):
+    global units
+    rounds = 0
+    clear = '\033c'
+    try:
+        print(clear + 'after 0 rounds with', ap, 'ap:')
+        show()
+        while True:
+            for unit in units:
+                if unit.hp > 0 and not unit.fight() and unit.move():
+                    unit.fight()
+            units = sorted((u for u in units if u.hp > 0), key=attrgetter('pos'))
+            rounds += 1
+            print(clear + 'after', rounds, 'rounds with', ap, 'ap:')
+            show()
+    except BattleLost as lost:
+        print(clear + 'after', rounds, 'rounds with', ap, 'ap:')
+        show()
+        winner = 'Goblins' if lost.team == 'E' else 'Elves'
+        return winner, rounds, sum(u.hp for u in units if u.hp > 0)
+
+def reset(elf_ap):
+    Unit.counts.clear()
+    grid = []
+    units = []
+    for i, cell in enumerate(startgrid):
+        if cell in (SPACE, WALL):
+            grid.append(cell)
+        else:
+            unit = Unit(i, cell.team, elf_ap if cell.team == 'E' else 3)
+            grid.append(unit)
+            units.append(unit)
+    return grid, units
+
+elf_ap = 3
+startgrid, w = parse(sys.stdin)
+grid, units = reset(elf_ap)
+startelves = sum(1 for u in units if u.team == 'E')
+
+# part 1
+winner, rounds, hp = simulate(elf_ap)
+print('Combat ends after', rounds, 'full rounds:')
+print(winner, 'win with', hp, 'hit points left')
+print('Outcome:', rounds, '*', hp, '=', rounds * hp)
+
+# part 2
+numelves = 0
+while winner != 'Elves' or numelves != startelves:
+    elf_ap += 1
+    grid, units = reset(elf_ap)
+    winner, rounds, hp = simulate(elf_ap)
+    numelves = sum(1 for u in units if u.team == 'E')
+
+print('Elves need', elf_ap, 'attack power not to let any elf die')
+print('Combat ends after', rounds, 'full rounds:')
+print(winner, 'win with', hp, 'hit points left')
+print('Outcome:', rounds, '*', hp, '=', rounds * hp)

input/15

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+################################
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+#######..##..###################
+#######....G##.#################
+#######GG..##...G.##############
+######.......G.G#.##############
+######...G.............#########
+#######............E.#.#########
+#####.#..............#.E########
+####.............#.###.#########
+####......G........####.########
+#####...................####.###
+##G#.........G#####......##..###
+#.......G....#######G.....#G####
+##...G......#########....##..###
+#...........#########........###
+#.G.......#.#########.E..##...##
+#..G##....#G#########..G......##
+########..G.#########.........##
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+#######.......#####.....E.....##
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+##########........##....#.....##
+#########......G......#####...##
+##########............####....##
+###########..E...#.....###.....#
+#############E................##
+#############....##..##.E..#..##
+###############.###..###...#.###
+###################......##.E###
+###################.......E.####
+################################