1 files changed, 76 insertions, 0 deletions
diff --git a/day11/src/main.rs b/day11/src/main.rs
new file mode 100644
index 0000000..c632acf
--- /dev/null
+++ b/day11/src/main.rs
@@ -0,0 +1,76 @@
+static INPUT: i32 = 9005;
+static WIDTH: usize = 300;
+static HEIGHT: usize = 300;
+
+type Grid = Vec<Vec<i32>>;
+
+fn build_grid() -> Grid {
+  let mut grid = vec![vec![0; WIDTH]; HEIGHT];
+  for y in 1..HEIGHT + 1 {
+    for x in 1..WIDTH + 1 {
+      if y == 5 && x == 3 {
+        print!("");
+      }
+      let rack_id: i32 = x as i32 + 10;
+      let mut level = rack_id * y as i32;
+      level += INPUT;
+      level *= rack_id;
+      level = nth_digit(level, 3);
+      level -= 5;
+
+      let xi = (x - 1) as usize;
+      let yi = (y - 1) as usize;
+      grid[yi][xi] = level;
+    }
+  }
+  grid
+}
+
+fn nth_digit(number: i32, n: u32) -> i32 {
+  (number % 10i32.pow(n)) / 10i32.pow(n - 1)
+}
+
+fn sum_subsquare(grid: &Grid, pos: (usize, usize), size: usize) -> i32 {
+  let mut total = 0i32;
+  for y in pos.1..pos.1 + size {
+    for x in pos.0..pos.0 + size {
+      total += grid[y][x];
+    }
+  }
+  total
+}
+
+fn visualize(grid: &Grid) {
+  for line in grid {
+    for ch in line {
+      print!("{} ", ch);
+    }
+    print!("\n");
+  }
+}
+
+fn main() {
+  let grid = build_grid();
+  // visualize(&grid);
+
+  let mut max_sum = std::i32::MIN;
+  let mut mx: usize = 0;
+  let mut my: usize = 0;
+  let mut msize: usize = 0;
+  for s in 1..301 {
+    println!("Debug: Running for size = {}", s);
+    for y in 0..HEIGHT - s + 1 {
+      for x in 0..WIDTH - s + 1 {
+        let sum = sum_subsquare(&grid, (x, y), s);
+        if sum > max_sum {
+          max_sum = sum;
+          mx = x;
+          my = y;
+          msize = s;
+        }
+      }
+    }
+  }
+
+  println!("Max sum {} at ({}, {}), size: {}", max_sum, mx + 1, my + 1, msize);
+}