added December 3.1 solution

december_3_1/.gitignore

@@ -0,0 +1 @@
+/target

december_3_1/Cargo.toml

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+[package]
+name = "december_3_1"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

december_3_1/src/main.rs

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+use std::fs::File;
+use std::io::{BufReader};
+use std::io::prelude::*;
+
+const NUMBER_OF_BITS: u8 = 12;
+
+fn main(){
+    let file = File::open("./input.txt").expect("Read failed");
+    let reader = BufReader::new(file);
+
+    let mut line_vec = Vec::new();
+    //let mut gamma_bits = Vec::new();
+
+    let all_lines = reader.lines();
+
+
+    for line in all_lines{
+        let line_as_string = line.unwrap();
+        line_vec.push(line_as_string);
+    }
+
+    for i in 0..NUMBER_OF_BITS {
+        let mut ones = 0;
+        let mut zeros = 0;
+        for l in &line_vec{
+            match l.chars().nth(i.into()).unwrap() {
+                '0' => zeros += 1,
+                '1' => ones += 1,
+                _ => println!("you should never be here"),
+            }
+        }
+        if ones > zeros {
+            print!("1");
+        } else {
+            print!("0");
+        }
+        println!();
+    }
+
+// 101001001011 2635
+// 010110110100 1460
+    
+
+    println!("Depth: {}, Horizontal: {}, Result: {}", 1,2,3);
+
+
+
+}