day06 quadratic equation

1 files changed, 7 insertions, 10 deletions

diff --git a/2023/day06.rs b/2023/day06.rs
index 92a631a..839c798 100644
--- a/2023/day06.rs
+++ b/2023/day06.rs
@@ -1,17 +1,14 @@
-#![allow(dead_code)]
-#![allow(unused_variables)]
-#![allow(unused_mut)]
+#![allow(non_snake_case)]
 use std::fs::File;
 use std::io::Read;
 
 fn get_opts(t: u64, d: u64) -> u64 {
-    let mut opts = 0;
-    for wait in 0..t {
-        if wait * (t - wait) > d {
-            opts += 1;
-        }
-    }
-    return opts;
+    let t = t as f64;
+    let d = d as f64;
+    let D = f64::sqrt((t * t - 4. * d) as f64);
+    let x1 = ((-t - D) / 2.).floor();
+    let x2 = ((-t + D) / 2.).floor();
+    (x2 - x1) as u64
 }
 
 fn main() {