Completed: 1, 2, 3, 4, 5.1, 6.1, 7, 8

day_06/src/main.rs

@@ -0,0 +1,57 @@
+use std::fs;
+
+use num_integer::Roots;
+
+fn main() {
+	let data = fs::read_to_string("input.txt").unwrap();
+	let (time_str, record_str) = data.split_once('\n').unwrap();
+	let times: Vec<i64> = time_str
+		.split_whitespace()
+		.skip(1)
+		.map(|t| t.parse().unwrap())
+		.collect();
+	let records: Vec<i64> = record_str
+		.split_whitespace()
+		.skip(1)
+		.map(|t| t.parse().unwrap())
+		.collect();
+	let answer = times
+		.iter()
+		.zip(records.iter())
+		.map(|(&time, &record)| beat(time, record))
+		.fold(1, |a, b| a * b);
+	println!("{answer}");
+
+	let big_time: i64 = time_str[7..].replace(' ', "").parse().unwrap();
+	let big_record: i64 = record_str[9..].trim().replace(' ', "").parse().unwrap();
+
+	/*
+	distance = held * (time - held)
+
+	held * (time - held) = record
+	held*time - held*held = record
+	held*time - held*held - record = 0
+	held*held - held*time + record = 0
+	*/
+	// let lower = ((time * time / 4) - record).sqrt() - time / 2;
+	// let upper = -((time * time / 4) - record).sqrt() - time / 2;
+	// println!("{lower} -> {upper}");
+}
+
+fn beat(time: i64, record: i64) -> i64 {
+	let mut variants = 0;
+	for t in 0..time {
+		let dist = t * (time - t);
+		if dist > record {
+			variants += 1;
+		}
+	}
+
+	let time = time as f64;
+	let record = record as f64;
+	let lower = ((time * time / 4.0) - record).sqrt() - time / 2.0;
+	let upper = -((time * time / 4.0) - record).sqrt() - time / 2.0;
+	println!("{lower} -> {upper}");
+
+	variants
+}