Do d01 using mapping and reducing iterators

d01/src/main.rs

@@ -12,6 +12,7 @@ where
 }
 
 fn part1() {
+    // My naiive attempt
     if let Ok(lines) = read_lines("input.txt") {
         let mut last_val: Option<i32> = None;
         let mut num_increase = 0;
@@ -39,6 +40,34 @@ fn part1() {
     }
 }
 
+fn part1mr() {
+    // Something more functional
+    let mut last_val: Option<i32> = None;
+    let num_increase = read_lines("input.txt")
+        .expect("Expected a file to read")
+        .map(|line| line.expect("Could not read line"))
+        .map(|line| {
+            line.parse::<i32>()
+                .expect(format!("Error parsing '{}' as in int", line).as_str())
+        })
+        .map(|value| {
+            let mut increase = 0;
+            if let Some(last_val) = last_val {
+                if value > last_val {
+                    increase = 1;
+                }
+            }
+            last_val = Some(value);
+            increase
+        })
+        .reduce(|num_increase, increase| num_increase + increase);
+
+    println!(
+        "Part 1 new, All done! Num increased {}",
+        num_increase.unwrap()
+    );
+}
+
 fn part2() {
     if let Ok(lines) = read_lines("input.txt") {
         let mut num_increase = 0;
@@ -59,7 +88,7 @@ fn part2() {
                             num_increase += 1;
                         }
                         sliding_values.push_back(val);
-                        println!("{}: {}", val, increase);
+                        // println!("{}: {}", val, increase);
                     }
                     Err(e) => println!("ERROR: Could not parse {}. {}", l, e),
                 }
@@ -70,7 +99,39 @@ fn part2() {
     }
 }
 
+fn part2mr() {
+    let mut sliding_values: VecDeque<i32> = VecDeque::with_capacity(3);
+    let num_increase = read_lines("input.txt")
+        .expect("Expected a file to read")
+        .map(|line| line.expect("Could not read line"))
+        .map(|line| {
+            line.parse::<i32>()
+                .expect(format!("Error parsing '{}' as in int", line).as_str())
+        })
+        .map(|value| {
+            let mut increase = 0;
+            if sliding_values.len() < 3 {
+                sliding_values.push_back(value);
+            } else {
+                let outgoing = sliding_values.pop_front().unwrap();
+                if value > outgoing {
+                    increase = 1;
+                }
+                sliding_values.push_back(value);
+            }
+            increase
+        })
+        .reduce(|num_increase, increase| num_increase + increase);
+
+    println!(
+        "Part 2 new, All done! Num increased {}",
+        num_increase.unwrap()
+    );
+}
+
 fn main() {
     part1();
+    part1mr();
     part2();
+    part2mr();
 }