AoC 2021: day3 solutions

2021/solutions/day_03.py

@@ -0,0 +1,127 @@
+"""AOC Day 3"""
+
+from os import read
+import pathlib
+import time
+
+TEST_INPUT = """00100
+11110
+10110
+10111
+10101
+01111
+00111
+11100
+10000
+11001
+00010
+01010"""
+
+def read_input(input_path: str) -> str:
+    """take input file path and return a str with the file's content"""
+    with open(input_path, 'r') as input_file:
+        input_data = input_file.read().strip()
+        return input_data
+
+def extract(input_data: str) -> list:
+    """take input data and return the appropriate data structure"""
+    return input_data.split('\n')
+
+def common_bits(lines: list) -> list:
+    """common_bits take a list of strings representing binary numbers and return a list of int one per digit. Each int can be 0, > 0 or < 0 if the number of 1s and 0s in that column are equal, more 1s or more 0s"""
+    col_num = len(lines[0])
+    columns = [0]*col_num
+    for line in lines:
+        bits = list(map(int, line))
+        for i, b in enumerate(bits):
+            if b == 0:
+                columns[i] -= 1
+            elif b == 1:
+                columns[i] += 1
+    return columns
+
+def common_bit(lines: list, column_number: int) -> int:
+    """common_bits take a list of strings representing binary numbers and a column number and return an int that can be 0, > 0 or < 0 if the number of 1s and 0s in that column are equal, more 1s or more 0s"""
+    cb = 0
+    for line in lines:
+        bits = list(map(int, line))
+        if bits[column_number] == 0:
+            cb -= 1
+        elif cb == 1:
+            cb += 1
+    return cb
+
+def part1(entries: list) -> int:
+    """part1 solver take the entries and return the part1 solution"""
+    gamma_rate = ''
+    epsilon_rate = ''
+    columns = common_bits(entries)
+
+    for common_bit in columns:
+        if common_bit > 0:
+            gamma_rate += '1'
+            epsilon_rate += '0'
+        elif common_bit < 0:
+            gamma_rate += '0'
+            epsilon_rate += '1'
+    
+    return int(gamma_rate, 2)*int(epsilon_rate, 2)
+
+def part2(entries: list) -> int:
+    """part2 solver take the entries and return the part2 solution"""
+    og_rating = ''
+    co2s_rating = ''
+
+    nums = entries.copy()
+    i = 0
+    while len(nums) > 1:
+        cb = common_bit(nums, i)
+        new_nums = list()
+        for num in nums:
+            if cb >= 0 and num[i] == '1':
+                new_nums.append(num)
+            elif cb < 0 and num[i] == '0':
+                new_nums.append(num)
+        nums = new_nums.copy()
+        i += 1
+    og_rating = nums[0]
+
+    nums = entries.copy()
+    i = 0
+    while len(nums) > 1:
+        cb = common_bit(nums, i)
+        new_nums = list()
+        for num in nums:
+            if cb >= 0 and num[i] == '0':
+                new_nums.append(num)
+            elif cb < 0 and num[i] == '1':
+                new_nums.append(num)
+        nums = new_nums.copy()
+        i += 1
+    co2s_rating = nums[0]
+
+    return int(og_rating, 2)*int(co2s_rating, 2)
+
+def test_input_day_03():
+    """pytest testing function"""
+    entries = extract(TEST_INPUT)
+    assert part1(entries) == 198
+    assert part2(entries) == 230
+
+def test_bench_day_03(benchmark):
+    """pytest-benchmark function"""
+    benchmark(main)
+
+def main():
+    """main function"""
+    input_path = str(pathlib.Path(__file__).resolve().parent.parent) + "/inputs/" + str(pathlib.Path(__file__).stem)
+    start_time = time.time()
+    input_data = read_input(input_path)
+    entries = extract(input_data)
+    print("Part 1: %d" % part1(entries))
+    print("Part 2: %d" % part2(entries))
+    end_time = time.time()
+    print("Execution time: %f" % (end_time-start_time))
+
+if __name__ == "__main__":
+    main()