3 files changed, 165 insertions, 0 deletions
diff --git a/users/Profpatsch/advent-of-code/2020/01/main.py b/users/Profpatsch/advent-of-code/2020/01/main.py
new file mode 100644
index 000000000000..e636017a54d5
--- /dev/null
+++ b/users/Profpatsch/advent-of-code/2020/01/main.py
@@ -0,0 +1,22 @@
+import sys
+
+l = []
+with open('./input', 'r') as f:
+    for line in f:
+        l.append(int(line))
+
+s = set(l)
+
+res=None
+for el in s:
+    for el2 in s:
+        if (2020-(el+el2)) in s:
+            res=(el, el2, 2020-(el+el2))
+            break
+
+if res == None:
+    sys.exit("could not find a number that adds to 2020")
+
+print(res)
+
+print(res[0] * res[1] * res[2])
diff --git a/users/Profpatsch/advent-of-code/2020/02/main.py b/users/Profpatsch/advent-of-code/2020/02/main.py
new file mode 100644
index 000000000000..e3b27c382a21
--- /dev/null
+++ b/users/Profpatsch/advent-of-code/2020/02/main.py
@@ -0,0 +1,77 @@
+import sys
+
+def parse(line):
+    a = line.split(sep=" ", maxsplit=1)
+    assert len(a) == 2
+    fromto = a[0].split(sep="-")
+    assert len(fromto) == 2
+    (from_, to) = (int(fromto[0]), int(fromto[1]))
+    charpass = a[1].split(sep=": ")
+    assert len(charpass) == 2
+    char = charpass[0]
+    assert len(char) == 1
+    pass_ = charpass[1]
+    assert pass_.endswith("\n")
+    pass_ = pass_[:-1]
+    return {
+        "from": from_,
+        "to": to,
+        "char": char,
+        "pass": pass_
+    }
+
+def char_in_pass(char, pass_):
+    return pass_.count(char)
+
+def validate_01(entry):
+    no = char_in_pass(entry["char"], entry["pass"])
+    if no < entry["from"]:
+        return { "too-small": entry }
+    elif no > entry["to"]:
+        return { "too-big": entry }
+    else:
+        return { "ok": entry }
+
+def char_at_pos(char, pos, pass_):
+    assert pos <= len(pass_)
+    return pass_[pos-1] == char
+
+def validate_02(entry):
+    one = char_at_pos(entry["char"], entry["from"], entry["pass"])
+    two = char_at_pos(entry["char"], entry["to"], entry["pass"])
+    if one and two:
+        return { "both": entry }
+    elif one:
+        return { "one": entry }
+    elif two:
+        return { "two": entry }
+    else:
+        return { "none": entry }
+
+
+res01 = []
+res02 = []
+with open("./input", 'r') as f:
+    for line in f:
+        p = parse(line)
+        res01.append(validate_01(p))
+        res02.append(validate_02(p))
+
+count01=0
+for r in res01:
+    print(r)
+    if r.get("ok", False):
+        count01=count01+1
+
+count02=0
+for r in res02:
+    print(r)
+    if r.get("one", False):
+        count02=count02+1
+    elif r.get("two", False):
+        count02=count02+1
+    else:
+        pass
+
+print("count 1: {}".format(count01))
+print("count 2: {}".format(count02))
diff --git a/users/Profpatsch/advent-of-code/2020/03/main.py b/users/Profpatsch/advent-of-code/2020/03/main.py
new file mode 100644
index 000000000000..4d6baf946c3e
--- /dev/null
+++ b/users/Profpatsch/advent-of-code/2020/03/main.py
@@ -0,0 +1,66 @@
+import itertools
+import math
+
+def tree_line(init):
+    return {
+        "init-len": len(init),
+        "known": '',
+        "rest": itertools.repeat(init)
+    }
+
+def tree_line_at(pos, tree_line):
+    needed = (pos + 1) - len(tree_line["known"])
+    # internally advance the tree line to the position requested
+    if needed > 0:
+        tree_line["known"] = tree_line["known"] \
+          + ''.join(
+            itertools.islice(
+                tree_line["rest"],
+                1+math.floor(needed / tree_line["init-len"])))
+    # print(tree_line)
+    return tree_line["known"][pos] == '#'
+
+def tree_at(linepos, pos, trees):
+    return tree_line_at(pos, trees[linepos])
+
+def slope_positions(trees, right, down):
+    line = 0
+    pos = 0
+    while line < len(trees):
+        yield (line, pos)
+        line = line + down
+        pos = pos + right
+
+trees = []
+with open("./input", 'r') as f:
+    for line in f:
+        line = line.rstrip()
+        trees.append(tree_line(line))
+
+# print(list(itertools.islice(trees[0], 5)))
+# print(list(map(
+#     lambda x: tree_at(0, x, trees),
+#     range(100)
+# )))
+# print(list(slope_positions(trees, right=3, down=1)))
+
+def count_slope_positions(trees, slope):
+    count = 0
+    for (line, pos) in slope:
+        if tree_at(line, pos, trees):
+            count = count + 1
+    return count
+
+print(
+        count_slope_positions(trees, slope_positions(trees, right=1, down=1))
+    *
+        count_slope_positions(trees, slope_positions(trees, right=3, down=1))
+    *
+        count_slope_positions(trees, slope_positions(trees, right=5, down=1))
+    *
+        count_slope_positions(trees, slope_positions(trees, right=7, down=1))
+    *
+        count_slope_positions(trees, slope_positions(trees, right=1, down=2))
+)
+
+# I realized I could have just used a modulo instead …