--- /dev/null
+#include_file "core/std/wasi"
+
+use package core
+use package core.str.reader as reader
+
+StartEnd :: struct { start: i32; end: i32; }
+
+find_contiguous_subarray_with_sum :: proc (nums: [..] u64, sum: u64) -> StartEnd {
+ start := 0;
+ end := 0;
+ con_sum: u64 = nums[0];
+
+ for i: 1 .. nums.count {
+ end += 1;
+ con_sum += nums[end];
+
+ if con_sum == sum do break;
+
+ while con_sum > sum && start <= end {
+ con_sum -= nums[start];
+ start += 1;
+
+ if con_sum == sum do break break;
+ }
+ }
+
+ return StartEnd.{ start, end };
+}
+
+main :: proc (args: [] cstring) {
+ contents := file.get_contents("input/day9.txt");
+ defer cfree(contents.data);
+
+ file := reader.make(contents);
+
+ nums: [..] u64;
+ array.init(^nums, 32);
+ defer array.free(^nums);
+
+ while !reader.empty(^file) {
+ num := reader.read_u64(^file);
+ array.push(^nums, num);
+ }
+
+ preamble_length :: 25;
+
+ invalid: u64;
+ for i: 0 .. nums.count {
+ if i < preamble_length do continue;
+
+ success := false;
+ for j: 0 .. preamble_length - 1 {
+ for k: j + 1 .. preamble_length {
+ if nums[i - j - 1] + nums[i - k - 1] == nums[i] {
+ success = true;
+ break break;
+ }
+ }
+ }
+
+ if !success {
+ invalid = nums[i];
+ break;
+ }
+ }
+
+ printf("Invalid number: %l\n", invalid);
+
+ se := find_contiguous_subarray_with_sum(nums, invalid);
+
+ max := array.fold_slice(nums.data[se.start .. se.end + 1], cast(u64) 0, math.max);
+ min := array.fold_slice(nums.data[se.start .. se.end + 1], cast(u64) max, math.min);
+
+ printf("Extrema sum: %l\n", min + max);
+}
projects / onyx-aoc-2020.git / commitdiff