Day 10

d10/main.odin

@@ -0,0 +1,77 @@
+package main
+
+import "core:math"
+import "core:slice"
+import "core:strconv"
+import "core:strings"
+import "core:bytes"
+import "core:fmt"
+import "core:os"
+
+import "../util"
+
+part_1 :: proc(lines: []string) {
+    result: i64 = 0
+    
+    numbers := slice.clone_to_dynamic(
+        slice.mapper(lines, proc(line: string) -> i64 {
+            num, ok := strconv.parse_i64(line); assert(ok)
+            return num
+    }))
+    slice.sort(numbers[:])
+
+    inject_at(&numbers, 0, 0)
+    append(&numbers, slice.last(numbers[:]) + 3)
+
+    ones: i64 = 0
+    threes: i64 = 0
+    for _, idx in numbers[:len(numbers)-1] {
+        switch numbers[idx+1] - numbers[idx] {
+        case 1: ones += 1
+        case 3: threes += 1
+        }
+    }
+    result = ones * threes
+
+    fmt.printfln("Part 1: %d", ones * threes)
+}
+
+part_2 :: proc(lines: []string) {
+    result: i64 = 1
+    
+    numbers := slice.clone_to_dynamic(
+        slice.mapper(lines, proc(line: string) -> i64 {
+            num, ok := strconv.parse_i64(line); assert(ok)
+            return num
+    }))
+    slice.sort(numbers[:])
+
+    inject_at(&numbers, 0, 0)
+    append(&numbers, slice.last(numbers[:]) + 3)
+    combinations := make([]i64, len(numbers))
+    combinations[len(combinations)-1] = 1
+
+    for idx1 := len(numbers) - 2 ; idx1 >= 0; idx1 -= 1 {
+        ways: i64 = 0
+        for idx2 := idx1 + 1; idx2 <= idx1 + 3; idx2 += 1 {
+            if idx2 >= len(numbers) do continue
+            if numbers[idx2] - numbers[idx1] <= 3 do ways += combinations[idx2]
+        }
+        combinations[idx1] = ways
+    }
+    result = combinations[0]
+
+    fmt.printfln("Part 2: %d", result)
+}
+
+main :: proc() {
+    context.allocator = context.temp_allocator
+    defer free_all(context.temp_allocator)
+
+    INPUT :: #load("input.txt", string)
+    lines := strings.split(INPUT, "\n")
+    lines = lines[:len(lines)-1]
+
+    part_1(lines)
+    part_2(lines)
+}