First commit for Rust work days 1&2

2016/day02/Cargo.lock

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+[root]
+name = "day02"
+version = "0.1.0"
+

2016/day02/Cargo.toml

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+[package]
+name = "day02"
+version = "0.1.0"
+authors = ["Russell Champoux <russell.champoux@thomsonreuters.com>"]
+
+[dependencies]

2016/day02/src/main.rs

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+use std::cmp;
+use std::io::Read;
+use std::fs::File;
+
+fn clamp(val: i32, lb: i32, ub: i32) -> i32 {
+    cmp::min(cmp::max(val, lb), ub)
+}
+
+fn state_to_val(state: (i32, i32)) -> i32 {
+    state.0 + 3 * state.1 + 1
+}
+
+fn state_to_new_val(state: (i32, i32)) -> char {
+    let val_map = [
+        [' ', ' ', '1', ' ', ' '],
+        [' ', '2', '3', '4', ' '],
+        ['5', '6', '7', '8', '9'],
+        [' ', 'A', 'B', 'C', ' '],
+        [' ', ' ', 'D', ' ', ' ']
+    ];
+    val_map[state.1 as usize][state.0 as usize]
+}
+
+fn part_1(input: &String) {
+    let mut state =  (1, 1);
+    // model a 3x3 grid that looks like
+    // 1 2 3
+    // 4 5 6
+    // 7 8 9
+    // where (0,0) starts in the upper left
+
+    //println!("Start at {}", state_to_val(state));
+    let mut answer = String::new();
+
+    for line in input.split('\n') {
+        for letter in line.trim().chars() {
+            match letter {
+                'R' => { state.0 = clamp(state.0 + 1, 0, 2); },
+                'L' => { state.0 = clamp(state.0 - 1, 0, 2); },
+                'U' => { state.1 = clamp(state.1 - 1, 0, 2); },
+                'D' => { state.1 = clamp(state.1 + 1, 0, 2); },
+                _ => println!("Unknown!")
+            }
+            //println!("Moved {} to {}", letter, state_to_val(state));
+        }
+        //println!("End on {}", state_to_val(state));
+        answer += &state_to_val(state).to_string();
+    }
+    println!("Part 1 answer is {}", answer);
+}
+
+fn part_2(input: &String) {
+    let mut state = (0, 2);
+    // model a 5x5 grid that looks like
+    //     1
+    //   2 3 4
+    // 5 6 7 8 9
+    //   A B C
+    //     D
+    // where blank spaces are invalid
+    let valid_map = [
+        [0, 0, 1, 0, 0],
+        [0, 1, 1, 1, 0],
+        [1, 1, 1, 1, 1],
+        [0, 1, 1, 1, 0],
+        [0, 0, 1, 0, 0]
+    ];
+    let mut answer = String::new();
+
+    for line in input.split('\n') {
+        for letter in line.trim().chars() {
+            let mut new_state = state;
+            match letter {
+                'R' => { new_state.0 = clamp(state.0 + 1, 0, 4); },
+                'L' => { new_state.0 = clamp(state.0 - 1, 0, 4); },
+                'U' => { new_state.1 = clamp(state.1 - 1, 0, 4); },
+                'D' => { new_state.1 = clamp(state.1 + 1, 0, 4); },
+                _ => println!("Unknown!")
+            }
+            // if this is a valid move position
+            if valid_map[new_state.1 as usize][new_state.0 as usize] == 1 {
+                state = new_state;
+                //println!("Moved {} to {}", letter, state_to_new_val(state));
+            }
+        }
+        //println!("End on {}", state_to_new_val(state));
+        answer.push(state_to_new_val(state));
+    }
+    println!("Part 2 answer is {}", answer);
+}
+
+fn main() {
+    let mut file = File::open("./data").expect("could not open file");
+    let mut input = String::new();
+    file.read_to_string(&mut input).expect("could not read file");
+
+    part_1(&input);
+    part_2(&input);
+}