2017 Day 01 Complete in Rust

2017/day01/day01.rs

@@ -0,0 +1,47 @@
+mod helpers;
+
+fn main() {
+    let input = helpers::read_std_in();
+    part1(input.clone());
+    part2(input.clone());
+}
+
+fn part1(input: String) {
+    let max = input.chars().count()-1;
+    let mut total = 0i32;
+    for (i, c) in input.chars().enumerate() {
+        let tst_idx = get_compare_idx(i, 1, max);
+        total += get_compare_result(c, input.chars().nth(tst_idx).unwrap());
+    }
+    println!("Part 1: {}", total);
+}
+
+fn part2(input: String) {
+    let max = input.chars().count()-1;
+    let mut total = 0i32;
+    for (i, c) in input.chars().enumerate() {
+        let tst_idx = get_compare_idx(i, (input.chars().count() / 2), max);
+        total += get_compare_result(c, input.chars().nth(tst_idx).unwrap());
+    }
+    println!("Part 2: {}", total);
+}
+
+fn get_compare_idx(curr: usize, add: usize, max: usize) -> usize {
+    let mut ret = curr + add;
+    if ret > max {
+        ret -= max+1;
+    }
+    return ret;
+}
+
+fn get_compare_result(c1: char, c2: char) -> i32 {
+    if c1 != c2 {
+        return 0;
+    }
+    match c1.to_digit(10) {
+        Some(v) => {
+            return v as i32;
+        },
+        None => 0,
+    }
+}

2017/day01/helpers.rs

@@ -0,0 +1,20 @@
+use std::io;
+
+pub fn read_std_in() -> String {
+    let mut input = String::new();
+    let mut done = false;
+    while !done {
+        match io::stdin().read_line(&mut input) {
+            Ok(n) => {
+                if n == 0 {
+                    done = true;
+                }
+            },
+            Err(error) => {
+                println!("error: {}", error);
+                done = true;
+            },
+        }
+    }
+    return String::from(input.trim());
+}

2017/day01/main.go

@@ -18,7 +18,7 @@ func main() {
 func part1(inp string) {
 	sum := 0
 	for k := range inp {
-		tstIdx := getCompareIndex(k, k+1, len(inp))
+		tstIdx := getCompareIndex(k, 1, len(inp))
 		sum += getCompareResult(inp[k], inp[tstIdx])
 	}
 	fmt.Println("Part 1:", sum)