day2, part 2

day02/src/main.rs

@@ -1,6 +1,7 @@
 fn main() {
     let input = std::fs::read_to_string("input").unwrap();
     println!("{}", pt1(&input));
+    println!("{}", pt2(&input));
 }
 
 #[derive(Debug, PartialEq, Eq, Clone, Copy)]
@@ -19,34 +20,58 @@ fn pt1(input: &str) -> usize {
     let input = parse(input);
     let mut safe = 0;
     for line in input.iter() {
-        let mut dir = None;
+        if safe_line(line) {
-        let mut last = None;
-        let mut lsafe = true;
-        for v in line.iter() {
-            if let Some(l) = last {
-                last = Some(v);
-                let d = v - l;
-                let s = Sign::new(d);
-                if let Some(p) = dir {
-                    if p != s {
-                        lsafe = false;
-                        break;
-                    }
-                }
-                dir = Some(s);
-                if d.abs() > 3 || d.abs() < 1 {
-                    lsafe = false;
-                    break;
-                }
-            } else {
-                last = Some(v);
-            }
-        }
-        if lsafe {
             safe += 1;
         }
     }
+    safe
+}
 
+fn safe_line(line: &[i64]) -> bool {
+    let mut dir = None;
+    let mut last = None;
+    let mut lsafe = true;
+    for v in line.iter() {
+        if let Some(l) = last {
+            last = Some(v);
+            let d = v - l;
+            let s = Sign::new(d);
+            if let Some(p) = dir {
+                if p != s {
+                    lsafe = false;
+                    break;
+                }
+            }
+            dir = Some(s);
+            if d.abs() > 3 || d.abs() < 1 {
+                lsafe = false;
+                break;
+            }
+        } else {
+            last = Some(v);
+        }
+    }
+    lsafe
+}
+
+fn pt2(input: &str) -> usize {
+    let input = parse(input);
+    let mut safe = 0;
+    for line in input.iter() {
+        if safe_line(line) {
+            safe += 1;
+        } else {
+            for i in 0..(line.len()) {
+                let left = &line[0..i];
+                let right = &line[(i + 1)..(line.len())];
+                let line: Vec<i64> = left.iter().cloned().chain(right.iter().cloned()).collect();
+                if safe_line(&line) {
+                    safe += 1;
+                    break;
+                }
+            }
+        }
+    }
     safe
 }
 
@@ -59,6 +84,7 @@ fn parse(input: &str) -> Vec<Vec<i64>> {
     lines
 }
 
+#[cfg(test)]
 mod test {
     use super::*;
 
@@ -74,4 +100,10 @@ mod test {
         let safe = pt1(INPUT);
         assert_eq!(2, safe);
     }
+
+    #[test]
+    fn tp2() {
+        let safe = pt2(INPUT);
+        assert_eq!(4, safe);
+    }
 }