2024 day 9 part 2 in javascript

2024/09/solution.js

@@ -49,7 +49,9 @@ const newfiles = files.concat(inserted)
   .filter(file => file.size > 0)
   .sort((a, b) => a.start > b.start)
 
-const checksum = newfiles.reduce((acc, current) => acc + (current.id * current.size * (current.start + (current.size - 1) / 2)), 0)
+const checksum = fs => fs.reduce((acc, current) =>
+  acc + (current.id * current.size * (current.start + (current.size - 1) / 2)),
+0)
 
-console.log(checksum)
+console.log(checksum(newfiles))
 

2024/09/solution2.js

@@ -0,0 +1,59 @@
+
+const input = (await Bun.file("input.txt").text()).trim()
+
+// const input = "2933133121414131402";
+/*
+ *  0123456789
+ *  0..1.....2
+ *  02.1
+ *  021
+ */
+
+
+const files = [];
+
+const spaces = [[], [], [], [], [], [], [], [], [], [], ];
+
+let pos = 0;
+for (let i = 0; i < input.length; i++ ) {
+  const size = parseInt(input[i])
+  if (size == 0) continue
+  if (i % 2 == 0) {
+    files.push({size, id: i / 2, start: pos,})
+  } else {
+    spaces[size].push(pos)
+  }
+  pos += size;
+}
+
+for (let i = files.length - 1; i >= 0; i--) {
+  const file = files[i]
+  const fitspaces = [];
+  for (let size = files[i].size; size <= 9; size ++ ) {
+    if (spaces[size].length == 0) {
+      continue
+    }
+    const start = spaces[size][0]
+    if (start > file.start) {
+      continue
+    }
+    fitspaces.push({size, start})
+  }
+  if (fitspaces.length == 0) continue
+  fitspaces.sort((a, b) => a.start > b.start)
+  const space = fitspaces[0]
+  files[i].start = space.start;
+  spaces[space.size].shift()
+  const newspacestart = space.start + files[i].size
+  const newspacesize = space.size - file.size
+  if (newspacesize == 0) continue
+  spaces[newspacesize].push(newspacestart)
+  spaces[newspacesize].sort((a, b) => a > b)
+}
+
+const checksum = fs => fs.reduce((acc, current) =>
+  acc + (current.id * current.size * (current.start + (current.size - 1) / 2)),
+0)
+
+console.log(checksum(files))
+