Finished part 1 of day 3 of advent of code

advent_of_code/3.rs

@@ -0,0 +1,82 @@
+use std::io::{self, BufRead};
+use std::path::Path;
+use std::fs::File;
+
+fn main(){
+    // Submarine is breaking, do diagnostics by checking power consumption
+    // Calculate gamma rate * epsilon rate
+    // Diagnostics are encoded by series of binary numbers
+
+    // Gamma rate is most common bit for each bit in the series
+    // Epsilon rate is the opposite, i.e. least common bit
+
+    // So when gamma rate would be 10011, epsilon rate automatically is 01100
+
+
+    println!("Advent of Code #3!\n");
+
+    let path = Path::new("./3.txt");
+    let display = path.display();
+
+    let file = match File::open(&path) {
+        Err(why) => panic!("Couldn't open {}: {}", display, why),
+        Ok(file) => file,
+    };
+
+    let lines = io::BufReader::new(file).lines();
+    let mut diagnostics = Vec::<Vec::<bool>>::new();
+
+    for line in lines{
+        let mut d_line = Vec::<bool>::new();
+        if let Ok(l) = line {
+            for c in l.chars() {
+                match c {
+                    '0' => d_line.push(false),
+                    '1' => d_line.push(true),
+                    _ => (),
+                }
+            }
+        }
+        diagnostics.push(d_line);
+    }
+
+    let mut line_numbers = 0;
+    let b_len = diagnostics[0].len();
+    let mut ones = vec![0; b_len];
+
+    for line in &diagnostics {
+        line_numbers += 1;
+
+        for i in 0 .. b_len {
+            match line[i] {
+                true => ones[i] += 1,
+                false => (),
+            }
+        }
+    }
+
+    let mut gamma_rate = Vec::new();
+    for n in ones {
+        if n > line_numbers / 2 {
+            gamma_rate.push(true);
+        } else {
+            gamma_rate.push(false);
+        }
+    }
+
+    let mut gamma_rate_decimal = 0;
+    let mut pow = 1;
+
+    gamma_rate.reverse();
+    for b in gamma_rate {
+        match b {
+            true => gamma_rate_decimal += pow,
+            false => (),
+        }
+        pow *= 2;
+    }
+
+    println!("Gamma rate in decimal is {}, epsilon rate in decimal is {}, yielding product of {}", 
+              gamma_rate_decimal, pow - gamma_rate_decimal - 1, 
+              gamma_rate_decimal * (pow - gamma_rate_decimal - 1));
+}