misc cleanup, minor readability fix, cargo clippy

src/day01.rs

@@ -3,7 +3,7 @@
 use crate::utils;
 use anyhow::{anyhow, Result};
 
-fn day01_part1(data: &[i64]) -> Result<i64> {
+fn part1(data: &[i64]) -> Result<i64> {
     for c in utils::combinations(2, data.len()) {
         if data[c[0]] + data[c[1]] == 2020 {
             return Ok(data[c[0]] * data[c[1]]);
@@ -12,7 +12,7 @@ fn day01_part1(data: &[i64]) -> Result<i64> {
     Err(anyhow!("no result found"))
 }
 
-fn day01_part2(data: &[i64]) -> Result<i64> {
+fn part2(data: &[i64]) -> Result<i64> {
     for c in utils::combinations(3, data.len()) {
         if data[c[0]] + data[c[1]] + data[c[2]] == 2020 {
             return Ok(data[c[0]] * data[c[1]] * data[c[2]]);
@@ -25,10 +25,10 @@ pub fn run() -> Result<(i64, i64)> {
     let data = utils::read_i64s("data/input-01.txt")?;
     let answers = utils::read_i64s("data/output-01.txt")?;
 
-    let p1 = day01_part1(&data)?;
+    let p1 = part1(&data)?;
     assert_eq!(p1, answers[0]);
 
-    let p2 = day01_part2(&data)?;
+    let p2 = part2(&data)?;
     assert_eq!(p2, answers[1]);
 
     Ok((p1, p2))

src/utils.rs

@@ -29,6 +29,22 @@ pub struct CombinationsState {
     done: bool,
 }
 
+pub fn combinations(t: usize, n: usize) -> CombinationsState {
+    let mut c = CombinationsState {
+        t,
+        c: vec![0; t + 2],
+        done: false,
+    };
+
+    // L1. Initialize
+    for i in 0..t {
+        c.c[i] = i;
+    }
+    c.c[t] = n;
+    c.c[t + 1] = 0;
+    c
+}
+
 impl Iterator for CombinationsState {
     type Item = Vec<usize>;
 
@@ -44,7 +60,7 @@ impl Iterator for CombinationsState {
         let mut j = 0;
         while (self.c[j] + 1) == self.c[j + 1] {
             self.c[j] = j;
-            j = j + 1;
+            j += 1;
         }
 
         // L4. Done?
@@ -53,25 +69,9 @@ impl Iterator for CombinationsState {
         };
 
         // L5. Increate c[j].
-        self.c[j] = self.c[j] + 1;
+        self.c[j] += 1;
 
         // return Some(visited) or None from L2 above
         ret
     }
 }
-
-pub fn combinations(t: usize, n: usize) -> CombinationsState {
-    let mut c = CombinationsState {
-        t: t,
-        c: vec![0; t + 2],
-        done: false,
-    };
-
-    // L1. Initialize
-    for i in 0..t {
-        c.c[i] = i;
-    }
-    c.c[t + 0] = n;
-    c.c[t + 1] = 0;
-    return c;
-}