day 13, solve linear equations

d13/part1.py

@@ -0,0 +1,19 @@
+import sys
+from aoc import nums
+
+MOVES = sorted([(i,j)
+    for i in range(1,101)
+        for j in range(1,101)
+], key=lambda x:3*x[0]+x[1])
+
+S = 0
+for i in sys.stdin.read().strip().split('\n\n'):
+    [a,b,p] = i.split("\n")
+    (xa, ya) = nums(a)
+    (xb, yb) = nums(b)
+    (xp, yp) = nums(p)
+    for (i,j) in MOVES:
+        if xa*i+xb*j==xp and ya*i+yb*j==yp:
+            S += 3*i+j
+            break
+print(S)

d13/part2.py

@@ -0,0 +1,31 @@
+import sys
+from aoc import nums
+import sympy as sym
+from sympy.core.numbers import Integer
+
+x,y = sym.symbols('x,y')
+
+def solve(a,b,p, part2=False):
+    (xa, ya) = a
+    (xb, yb) = b
+    (xp, yp) = p
+    T = 10_000_000_000_000 if part2 else 0
+    eq1 = sym.Eq(x*xa+y*xb, xp+T)
+    eq2 = sym.Eq(x*ya+y*yb, yp+T)
+    result = sym.solve([eq1,eq2],(x,y))
+    if type(result[x]) is not Integer or type(result[y]) is not Integer:
+        return 0
+    elif not part2 and (result[x]>100 or result[y]>100):
+        return 0
+    else:
+        return result[x]*3 + result[y]
+
+S1 = S2 = 0
+for i in sys.stdin.read().strip().split('\n\n'):
+    [a,b,p] = i.split("\n")
+    a = nums(a)
+    b = nums(b)
+    p = nums(p)
+    S1 += solve(a,b,p)
+    S2 += solve(a,b,p,part2=True)
+print(S1, S2)