Add src/06part2.rs

src/06part2.rs

@@ -0,0 +1,27 @@
+use std::fs;
+
+fn main() {
+    let file_path = "input/06input.txt";
+    let contents = fs::read_to_string(file_path).expect("should read file");
+    let mut lines = contents.lines();
+    let time_str = lines.next().unwrap().strip_prefix("Time:      ").unwrap();
+    let times = time_str.split_whitespace().fold(String::new(), |acc, x| acc + x).parse::<u128>().ok().unwrap();
+    let distance_str = lines.next().unwrap().strip_prefix("Distance:  ").unwrap();
+    let distances = distance_str.split_whitespace().fold(String::new(), |acc, x| acc + x).parse::<u128>().ok().unwrap();
+    let mut total = 1;
+    let mut j = 0;
+    let mut k = times-1;
+    loop {
+        if j*(times-j) <= distances {
+            j += 1;
+        }
+        if k*(times-k) <= distances {
+            k -= 1;
+        }
+        if j*(times-j) > distances && k*(times-k) > distances {
+            total *= k - j + 1;
+            break;
+        }
+    }
+    println!("{}", total);
+}