day03 completed

Author: pietroppeter

2021/day03.nim

@@ -0,0 +1,86 @@
+include prelude
+import sugar
+
+var
+  countOnes: array[12, int]
+  n: int
+
+for line in "2021/input03.txt".lines:
+  inc n
+  for i, c in line:
+    if c == '1':
+      inc countOnes[i]
+
+echo countOnes
+echo n
+
+var gamma, epsilon: string
+for k in countOnes:
+  if k > 500:
+    gamma &= "1"
+    epsilon &= "0"
+  else:
+    gamma &= "0"
+    epsilon &= "1"
+
+echo parseBinInt(gamma)*parseBinInt(epsilon)
+
+# part 2
+let
+  binNums = "2021/input03.txt".lines.toSeq
+  testNums = """
+00100
+11110
+10110
+10111
+10101
+01111
+00111
+11100
+10000
+11001
+00010
+01010""".splitLines.toSeq
+
+func lifeSupport(nums: seq[string], oxy=true): int =
+  var
+    nums = nums  # idiomatic
+    i = 0
+    zeros, ones: seq[int]
+  while nums.len > 1:
+    zeros = @[]  # zeros, ones = @[] does not work
+    ones = @[]
+    for j, num in nums:
+      if num[i] == '1':
+        ones.add j
+      else:
+        zeros.add j
+    #dump ones
+    #dump zeros
+    if oxy:
+      if ones.len >= zeros.len:
+        nums = collect:
+          for j in ones:
+            nums[j]
+      else:
+        nums = collect:
+          for j in zeros:
+            nums[j]
+    else:
+      if zeros.len <= ones.len:
+        nums = collect:
+          for j in zeros:
+            nums[j]
+      else:
+        nums = collect:
+          for j in ones:
+            nums[j]
+    inc i
+    #debugEcho nums
+  assert nums.len == 1
+  return parseBinInt(nums[0])
+
+func solve2(nums: seq[string]): int =
+  lifeSupport(nums)*lifeSupport(nums, false)
+echo solve2 testNums
+echo solve2 binNums