day 5 done

2024/05/part 1 solution.py

@@ -0,0 +1,86 @@
+testing = 0
+if not testing:
+    with open(r"2024/05\input.txt", "r") as file:
+        input = file.read()
+else:
+    input = """47|53
+97|13
+97|61
+97|47
+75|29
+61|13
+75|53
+29|13
+97|29
+53|29
+61|53
+97|53
+61|29
+47|13
+75|47
+97|75
+47|61
+75|61
+47|29
+75|13
+53|13
+
+75,47,61,53,29
+97,61,53,29,13
+75,29,13
+75,97,47,61,53
+61,13,29
+97,13,75,29,47"""
+
+# first we split the input into the two parts
+# the first part is the "rules" and the second part is the "updates"
+rules, updates = input.split("\n\n")
+# print(rules)
+# print('^v^v^v^')
+# print(updates)
+# for each rule the left side is the page that must come before the right side
+# to check the updates are correct we need to check that the left side of the update is before the right side
+# if all updatesare correct then the rules are correct and we need to store the 'middle' number
+
+# lets assign each update to a list of numbers
+update_lists = []
+for update in updates.split("\n"):
+    update_lists.append(list(map(int, update.split(","))))
+#print(update_lists)
+
+# lets also assign the rules to a list of tuples of numbers
+rule_tuples = []
+for rule in rules.split("\n"):
+    rule_tuples.append(tuple(map(int, rule.split("|"))))
+#print(rule_tuples)
+
+valid_updates = []
+# now for each update we need to check that it follows the rules
+for update in update_lists:
+    valid = True
+    # we need to check that the update is ordered correctly based on the rules
+    for rule in rule_tuples:
+        # if the update does not contain the any number in the rules we can ignore that rule
+        if rule[0] not in update or rule[1] not in update:
+            continue
+        # if the left side is before the right side then we can break out of the loop
+        if update.index(rule[0]) < update.index(rule[1]):
+            continue
+        # if the right side is before the left side then we can break out of the loop
+        if update.index(rule[0]) > update.index(rule[1]):
+            valid = False
+            break
+    if valid:
+        valid_updates.append(update)
+
+print('The valid updates are',valid_updates)
+
+numbers_to_sum = []
+for update in valid_updates:
+    update_len = len(update)
+    # we need to find the middle number
+    middle = update_len // 2
+    numbers_to_sum.append(update[middle])
+
+print('The numbers to sum are',numbers_to_sum)
+print('The sum of the numbers is',sum(numbers_to_sum))

2024/05/part 2 solution.py

@@ -0,0 +1,106 @@
+testing = 0
+if not testing:
+    with open(r"2024/05\input.txt", "r") as file:
+        input = file.read()
+else:
+    input = """47|53
+97|13
+97|61
+97|47
+75|29
+61|13
+75|53
+29|13
+97|29
+53|29
+61|53
+97|53
+61|29
+47|13
+75|47
+97|75
+47|61
+75|61
+47|29
+75|13
+53|13
+
+75,47,61,53,29
+97,61,53,29,13
+75,29,13
+75,97,47,61,53
+61,13,29
+97,13,75,29,47"""
+
+# first we split the input into the two parts
+# the first part is the "rules" and the second part is the "updates"
+rules, updates = input.split("\n\n")
+# print(rules)
+# print('^v^v^v^')
+# print(updates)
+# for each rule the left side is the page that must come before the right side
+# to check the updates are correct we need to check that the left side of the update is before the right side
+# if all updatesare correct then the rules are correct and we need to store the 'middle' number
+
+# lets assign each update to a list of numbers
+update_lists = []
+for update in updates.split("\n"):
+    update_lists.append(list(map(int, update.split(","))))
+#print(update_lists)
+
+# lets also assign the rules to a list of tuples of numbers
+rule_tuples = []
+for rule in rules.split("\n"):
+    rule_tuples.append(tuple(map(int, rule.split("|"))))
+#print(rule_tuples)
+
+def check_and_rearrange(update, rule):
+    if rule[0] in update and rule[1] in update:
+        index_0 = update.index(rule[0])
+        index_1 = update.index(rule[1])
+        if index_0 > index_1:
+            # Swap the elements to follow the rule
+            update[index_0], update[index_1] = update[index_1], update[index_0]
+            return False  # Indicate that a change was made
+    return True  # No change needed
+
+#first pass, any updates that pass the rules are valid
+valid_updates = []
+incorrectly_ordered_updates = []
+for update in update_lists:
+    valid = True
+    # we need to check that the update is ordered correctly based on the rules
+    for rule in rule_tuples:
+        # if the update does not contain the any number in the rules we can ignore that rule
+        if rule[0] not in update or rule[1] not in update:
+            continue
+        # if the left side is before the right side then we can break out of the loop
+        if update.index(rule[0]) < update.index(rule[1]):
+            continue
+        # if the right side is before the left side then we can break out of the loop
+        if update.index(rule[0]) > update.index(rule[1]):
+            valid = False
+            incorrectly_ordered_updates.append(update)
+            break
+    if valid:
+        valid_updates.append(update)
+
+# reorder the incorrectly-ordered updates
+for update in incorrectly_ordered_updates:
+    changed = True
+    while changed:
+        changed = False
+        for rule in rule_tuples:
+            if not check_and_rearrange(update, rule):
+                changed = True
+
+
+# Extract the middle number from each reordered update and sum them
+numbers_to_sum = []
+for update in incorrectly_ordered_updates:
+    update_len = len(update)
+    middle = update_len // 2
+    numbers_to_sum.append(update[middle])
+
+print('The numbers to sum are', numbers_to_sum)
+print('The sum of the numbers is', sum(numbers_to_sum))