From 484491426db20b1e0496b28afa3d8accb14c640f Mon Sep 17 00:00:00 2001
From: Andrew Ekstedt <andrew.ekstedt@gmail.com>
Date: Mon, 9 Dec 2024 17:46:27 +0000
Subject: [PATCH] day 9 part 2

it seemed easier to go for a sparse implementation than try to make the
dense implementation from part 1 work
---
 day09/sol.py | 40 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 40 insertions(+)

diff --git a/day09/sol.py b/day09/sol.py
index 9297f42..7a5e8c7 100644
--- a/day09/sol.py
+++ b/day09/sol.py
@@ -40,6 +40,46 @@ def solve(input):
         t += i*x
     print(t)
 
+def solve2(input):
+    freelist = []
+    blocks = {}
+    pos = 0
+    id = 0
+    for i in range(len(input)):
+        n = int(input[i])
+        if i % 2 == 0:
+            blocks[id] = (pos, n)
+            id += 1
+        else:
+            freelist.append((pos, n))
+        pos += n
+
+    lastid = id
+    for id in range(lastid-1,-1,-1):
+        bpos, blen = blocks[id]
+        for i in range(len(freelist)):
+            fpos, flen = freelist[i]
+            if bpos < fpos:
+                break
+            if blen <= flen:
+                blocks[id] = (fpos, blen)
+                if flen == blen:
+                    del freelist[i]
+                else:
+                    freelist[i] = (fpos+blen, flen-blen)
+                break
+
+    t = 0
+    for id in blocks:
+        i, n = blocks[id]
+        for x in range(i,i+n):
+            t += id*x
+
+    print(t)
+
 
 solve(sample)
 solve(input)
+
+solve2(sample)
+solve2(input)