Day13

src/day13.rs

@@ -0,0 +1,105 @@
+use std::io;
+
+fn try_vertical(rows: &Vec<Vec<char>>, c: usize, smudge: bool) -> bool {
+  let mut left = c - 1;
+  let mut right = c;
+
+  let mut one_err = false;
+
+  loop {
+    for row in rows {
+      if row[left] != row[right] {
+        if smudge && !one_err {
+          one_err = true;
+          continue;
+        }
+        return false;
+      }
+    }
+    if left == 0 || right == rows[0].len() - 1 {
+      if smudge {
+        return one_err;
+      }
+      return true;
+    }
+    left -= 1;
+    right += 1;
+  }
+}
+
+fn find_vertical(rows: &Vec<Vec<char>>, smudge: bool) -> Option<usize> {
+  for i in 1..rows[0].len() {
+    if try_vertical(rows, i, smudge) {
+      return Some(i);
+    }
+  }
+  None
+}
+
+fn try_horizontal(rows: &Vec<Vec<char>>, r: usize, smudge: bool) -> bool {
+  let mut top = r - 1;
+  let mut bottom = r;
+
+  let mut one_err = false;
+  loop {
+    for i in 0..rows[0].len() {
+      if rows[top][i] != rows[bottom][i] {
+        if smudge && !one_err {
+          one_err = true;
+          continue;
+        }
+        return false;
+      }
+    }
+    if top == 0 || bottom == rows.len() - 1 {
+      if smudge {
+        return one_err;
+      }
+      return true;
+    }
+    top -= 1;
+    bottom += 1;
+  }
+}
+
+fn find_horizontal(rows: &Vec<Vec<char>>, smudge: bool) -> Option<usize> {
+  for i in 1..rows.len() {
+    if try_horizontal(rows, i, smudge) {
+      return Some(i);
+    }
+  }
+  None
+}
+
+pub fn summarize(smudge: bool) -> usize {
+  let mut buffer = String::new();
+
+  while io::stdin().read_line(&mut buffer).unwrap() > 0 {}
+
+  let valleys = buffer.split("\n\n");
+
+  let mut sum = 0;
+  for valley in valleys {
+    let rowsplit = valley.split("\n");
+    let mut rows = Vec::new();
+    for row in rowsplit {
+      if row.len() > 0 {
+        rows.push(row.chars().collect());
+      }
+    }
+    match find_vertical(&rows, smudge) {
+      Some(x) => {
+        sum += x;
+        continue;
+      }
+      _ => {}
+    }
+    match find_horizontal(&rows, smudge) {
+      Some(x) => {
+        sum += 100 * x;
+      }
+      _ => panic!("No match mound {:?}", rows),
+    }
+  }
+  sum
+}

src/main.rs

@@ -4,6 +4,7 @@ mod day1;
 mod day10;
 mod day11;
 mod day12;
+mod day13;
 mod day2;
 mod day3;
 mod day4;
@@ -44,6 +45,8 @@ fn main() {
     "day11b" => println!("Sum: {}", day11::sum_lengths(999999)),
     "day12a" => println!("Sum: {}", day12::sum_arrangements(false)),
     "day12b" => println!("Sum: {}", day12::sum_arrangements(true)),
+    "day13a" => println!("Summary: {}", day13::summarize(false)),
+    "day13b" => println!("Summary: {}", day13::summarize(true)),
     _ => println!("Unrecognized day: {}", args[1]),
   }
 }