Day1 works - no unit tests yet

src/day1.rs

@@ -0,0 +1,79 @@
+use std::collections::HashSet;
+
+const DEBUG : bool = false;
+
+pub struct Data {
+    input : Vec<i32>,
+}
+
+impl Data {
+    pub fn new() -> Data {
+        Data {
+            input : Vec::new(),
+        }
+    }
+
+    pub fn parse(&mut self, input: String) {
+        for line in input.split("\n") {
+            let mut sline = line.to_string();
+            if DEBUG {
+                print!("{} -> ", sline);
+            }
+            if sline.len() >= 2 {
+                let mult: i32 = match sline.remove(0) {
+                    '+' => 1,
+                    '-' => -1,
+                    _ => 0,
+                };
+                if DEBUG {
+                    print!("{}, {}", mult, sline.parse::<i32>().unwrap());
+
+                }
+                self.input.push(mult * sline.parse::<i32>().unwrap());
+            }
+        }
+        if DEBUG {
+            for f in self.input.iter() {
+                print!("{} ",f);
+            }
+        }
+    }
+
+    pub fn challenge1(&mut self) -> i32 {
+        let mut result : i32 = 0;
+        for f in self.input.iter() {
+            result = result + f;
+        }
+        result
+    }
+
+    pub fn challenge2(&mut self) -> i32 {
+        let mut dup : HashSet<i32> = HashSet::new();
+        let mut found : bool = false;
+        let mut result : i32 = 0;
+        while !found {
+            for i in self.input.clone() {
+                if !found {
+                    result = result + i;
+
+                    if dup.contains(&result) {
+                        found = true;
+                        if DEBUG {
+                            println!("{} == elem", result);
+                        }
+                    }
+                    else {
+                        dup.insert(result);
+                        if DEBUG {
+                            for elem in dup.clone() {
+                                print!("{} ", elem);
+                            }
+                            println!("{} != elem", result);
+                        }
+                    }
+                }
+            }
+        }
+        result
+    }
+}

src/main.rs

@@ -1,3 +1,29 @@
+use std::fs::File;
+use std::io::Read;
+
+mod day1;
+
 fn main() {
-    println!("Hello, world!");
+    match read_file("day1.txt") {
+        Ok(input) => {
+            let mut d1 = day1::Data::new();
+            d1.parse(input);
+            println!("Day1 Challenge1 result = {}",d1.challenge1());
+            println!("Day1 Challenge2 result = {}",d1.challenge2());
+        },
+        Err(msg) => {println!("Error: {}", msg);},
+    }
+}
+
+fn read_file(filename: &str) -> Result<String,std::io::Error> {
+    match File::open(filename) {
+        Ok(mut file) => {
+            let mut input = String::new();
+            match file.read_to_string(&mut input) {
+                Ok(_) => Ok(input),
+                Err(msg) => Err(msg),
+            }
+        },
+        Err(msg) => Err(msg),
+    }
 }