Added 2021 (python)

2021/03/prog.py

@@ -0,0 +1,55 @@
+VERBOSE = False
+
+def get_input(sample = False, part = 1):
+    global n_bits
+    with open(f'sample_p{part}' if sample else 'input', 'r') as f:
+        tmp = f.readlines()
+        n_bits = len(tmp[0]) - 1
+        return [int(line.strip(), 2) for line in tmp]
+
+def verbose(s):
+    if VERBOSE:
+        print(s)
+
+
+def filter_by(most, inp):
+    global n_bits
+    for i in range(n_bits - 1, -1, -1):
+        dic = {0: [], 1: []}
+        for n in inp:
+            dic[(n >> i) & 1].append(n)
+
+        verbose(dic)
+        if len(dic[1]) >= len(dic[0]):
+            inp = dic[1 if most else 0][:]
+        else:
+            inp = dic[0 if most else 1][:]
+
+        if len(inp) == 1:
+            return inp[0]
+    
+def result(inp, part = 1):
+    global n_bits
+    if part == 1:
+        # print(n_bits)
+        tot = len(inp)
+        gamma = eps = 0
+        for i in range(n_bits):
+            ones = 0
+            for n in inp:
+                ones += (n >> i) & 1
+
+            a = 1 if ones > tot/2 else 0
+            gamma |= a << i
+
+        eps = (2**n_bits - 1) ^ gamma
+        return eps * gamma
+    else:
+        ox = filter_by(True, inp)
+        co = filter_by(False, inp)
+        verbose(f"{ox = }, {co = }")
+        return ox * co
+
+
+if __name__ == "__main__":
+    print(result(get_input(), part = 2))

2021/03/sample_p1

@@ -0,0 +1,12 @@
+00100
+11110
+10110
+10111
+10101
+01111
+00111
+11100
+10000
+11001
+00010
+01010

2021/03/test.py

@@ -0,0 +1,13 @@
+from prog import *
+import unittest
+
+class Tests(unittest.TestCase):
+    def test_input(self):
+        self.assertEqual(get_input(sample = True), [4, 30, 22, 23, 21, 15, 7, 28, 16, 25, 2, 10])
+        
+    def test_part1(self):
+        self.assertEqual(result(get_input(sample = True)), 198)
+
+    def test_part2(self):
+        self.assertEqual(result(get_input(sample = True), part = 2), 230)
+