2024/9/odin: solve part 1

.gitignore

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+input.txt
+input

2024/9/odin/example.txt

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+2333133121414131402

2024/9/odin/main.odin

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+package aoc2024day9
+
+import "core:container/queue"
+import "core:fmt"
+import "core:os"
+import "core:slice"
+import "core:strconv"
+import "core:unicode"
+
+PUZZLE_INPUT_PATH :: "input.txt"
+EXAMPLE_INPUT_PATH :: "example.txt"
+
+main :: proc() {
+	path := len(os.args) == 2 ? os.args[1] : PUZZLE_INPUT_PATH
+	input := string(os.read_entire_file_from_filename(path) or_else panic("damn"))
+
+	fmt.println("part 1:", part1(input))
+	fmt.println("part 2:", part2(input))
+}
+
+part2 :: proc(input: string) -> int {
+	mem: [dynamic]int
+	defer delete(mem)
+	free: map[int]int // start_index -> free_space_interval_delta
+	defer delete(free)
+	filesizes: map[int]int // fileid -> block_count
+	defer delete(filesizes)
+
+	next_fileid := 0
+	memptr := 0
+
+	for r, i in input {
+		if !unicode.is_digit(r) {continue}
+		d := strconv._digit_value(r)
+		if i % 2 == 0 { 	// files
+			for j := 0; j < d; j += 1 {
+				append(&mem, next_fileid)
+				memptr += 1
+				filesizes[next_fileid] = j + 1
+			}
+			next_fileid += 1
+		} else { 	// free
+			for j := 0; j < d; j += 1 {
+				append(&mem, -1)
+				free[memptr - j] = j + 1
+				memptr += 1
+			}
+		}
+	}
+
+	// fmt.println(free)
+	// fmt.println(filesizes)
+
+	used: [dynamic]int
+	defer delete(used)
+
+	#reverse for fid, i in mem {
+		if fid < 0 || slice.contains(used[:], fid) {continue}
+		append(&used, fid)
+		move := false
+		size := filesizes[fid]
+		for f, j in mem {
+			if f >= 0 || !(j in free) {continue} 	// TODO: scary slow
+			t := free[j]
+			if t >= size {
+				move = true
+				for k in 0 ..< size {
+					mem[j + k] = fid
+				}
+				free[j + size] = t - size
+				break
+			}
+		}
+		if move {
+			for k in 0 ..< size {
+				mem[i - k] = -2
+			}
+		}
+		for m in mem {
+			if m < 0 {
+				fmt.print("x")
+			} else {
+				fmt.print(m)
+			}
+		}
+		fmt.println()
+	}
+
+	// for fid := next_fileid - 1; fid > 0; fid -= 1 {
+	// 	size := filesizes[fid]
+	// 	memptr -= size
+	// }
+
+	// keys := slice.map_keys(free) or_else panic("damn2")
+	// slice.sort(keys)
+	// ptr := 0
+	// #reverse for fileid, i in mem {
+	// 	if fileid < 0 {continue}
+	// 	cur := mem[memptr - 1]
+	// 	target := filesizes[cur]
+	// 	for start, j in keys[ptr:] {
+	// 		delta := free[start]
+	// 		if delta < target {continue}
+	// 		end := delta + start
+	// 	}
+	// }
+
+	// #reverse for fileid, i in mem {
+	// 	f := queue.peek_front(&free)^
+	// 	if queue.len(free) <= 0 || f >= len(mem) {break}
+	// 	if fileid >= 0 {
+	// 		mem[f] = fileid
+	// 		queue.pop_front(&free)
+	// 	}
+	// 	pop(&mem)
+	// }
+
+	sum := 0
+	for fileid, i in mem {
+		if fileid < 0 {continue}
+		sum += fileid * i
+	}
+
+	return sum
+}
+
+part1 :: proc(input: string) -> int {
+	mem: [dynamic]int
+	defer delete(mem)
+	free: queue.Queue(int)
+	queue.init(&free)
+	defer queue.destroy(&free)
+
+	next_fileid := 0
+	memptr := 0
+
+	for r, i in input {
+		if !unicode.is_digit(r) {continue}
+		d := strconv._digit_value(r)
+		if i % 2 == 0 { 	// files
+			for j := 0; j < d; j += 1 {
+				append(&mem, next_fileid)
+				memptr += 1
+			}
+			next_fileid += 1
+		} else { 	// free
+			for j := 0; j < d; j += 1 {
+				append(&mem, -1)
+				queue.push_back(&free, memptr)
+				memptr += 1
+			}
+		}
+	}
+
+	#reverse for fileid, i in mem {
+		f := queue.peek_front(&free)^
+		if queue.len(free) <= 0 || f >= len(mem) {break}
+		if fileid >= 0 {
+			mem[f] = fileid
+			queue.pop_front(&free)
+		}
+		pop(&mem)
+	}
+
+	sum := 0
+	for fileid, i in mem {
+		if fileid < 0 {continue}
+		sum += fileid * i
+		// fmt.println(fileid, i)
+	}
+
+	return sum
+}