Replace format("{}") with .to_string() where possible.

2018/src/day01.rs

@@ -21,7 +21,7 @@ impl common::Solution for Day01 {
             .map(|x| x.unwrap().parse::<i32>().unwrap())
             .sum();
 
-        format!("{}", sum)
+        sum.to_string()
     }
 
     fn part2(&mut self, input: &mut io::Read) -> String {
@@ -37,7 +37,7 @@ impl common::Solution for Day01 {
             for amount in &nums {
                 sum += amount;
                 if freqs.contains(&sum) {
-                    return format!("{}", sum);
+                    return sum.to_string();
                 } else {
                     freqs.insert(sum);
                 }

2018/src/day02.rs

@@ -50,7 +50,7 @@ impl common::Solution for Day02 {
             }
         }
 
-        return format!("{}", twos * threes);
+        (twos * threes).to_string()
     }
 
     fn part2(&mut self, input: &mut io::Read) -> String {

2018/src/day03.rs

@@ -78,7 +78,7 @@ impl common::Solution for Day03 {
             .filter(|&&x| x > 1)
             .count();
 
-        format!("{}", multi_claim)
+        multi_claim.to_string()
     }
 
     fn part2(&mut self, input: &mut io::Read) -> String {
@@ -89,7 +89,7 @@ impl common::Solution for Day03 {
             .position(|x| x.range().all(|x| claims[&x] == 1))
             .unwrap();
 
-        format!("{}", uncontested + 1)
+        (uncontested + 1).to_string()
     }
 }
 

2018/src/day04.rs

@@ -92,7 +92,7 @@ impl Day04 {
         let best_minute = sleepers[best_sleeper].iter().enumerate()
             .max_by(|&(_, a), &(_, b)| a.cmp(b)).unwrap().0;
 
-        format!("{}", best_sleeper * (best_minute as usize))
+        (best_sleeper * (best_minute as usize)).to_string()
     }
 }
 

2018/src/day05.rs

@@ -34,7 +34,7 @@ impl common::Solution for Day05 {
         input.read_to_end(&mut data).expect("Can't read input!");
         common::trim_back(&mut data);
 
-        format!("{}", Day05::reduce(data))
+        Day05::reduce(data).to_string()
     }
 
     fn part2(&mut self, input: &mut Read) -> String {
@@ -46,7 +46,7 @@ impl common::Solution for Day05 {
             .map(Day05::reduce)
             .min().unwrap();
 
-        format!("{}", min_len)
+        min_len.to_string()
     }
 }
 

2018/src/day06.rs

@@ -111,11 +111,11 @@ impl Solution for Day06 {
             .filter_map(claim_filter)
             .filter(|x| !infinite.contains(x)).grouping_count();
 
-        format!("{}", counts.values().max().unwrap())
+        counts.values().max().unwrap().to_string()
     }
 
     fn part2(&mut self, input: &mut Read) -> String {
-        format!("{}", self.part2_with_limit(input, 10_000))
+        self.part2_with_limit(input, 10_000).to_string()
     }
 }
 

2018/src/day07.rs

@@ -128,7 +128,7 @@ impl Solution for Day07 {
     }
 
     fn part2(&mut self, input: &mut Read) -> String {
-        format!("{}", self.part2_parametrized(input, 60, 5))
+        self.part2_parametrized(input, 60, 5).to_string()
     }
 }
 

2018/src/day08.rs

@@ -64,7 +64,7 @@ impl Solution for Day08 {
         let data: Vec<usize> = data.trim().split(' ').map(|x| x.parse().unwrap()).collect();
         let (result, _) = total1(&data);
 
-        format!("{}", result)
+        result.to_string()
     }
 
     fn part2(&mut self, input: &mut Read) -> String {
@@ -73,7 +73,7 @@ impl Solution for Day08 {
         let data: Vec<usize> = data.trim().split(' ').map(|x| x.parse().unwrap()).collect();
         let (result, _) = total2(&data);
 
-        format!("{}", result)
+        result.to_string()
     }
 }
 

2018/src/day09.rs

@@ -55,13 +55,13 @@ impl Solution for Day09 {
     fn part1(&mut self, input: &mut Read) -> String {
         let (elves, marbles) = Day09::read_input(input);
 
-        format!("{}", winning_marbles(elves, marbles))
+        winning_marbles(elves, marbles).to_string()
     }
 
     fn part2(&mut self, input: &mut Read) -> String {
         let (elves, marbles) = Day09::read_input(input);
 
-        format!("{}", winning_marbles(elves, marbles * 100))
+        winning_marbles(elves, marbles * 100).to_string()
     }
 }
 

2018/src/day10.rs

@@ -117,7 +117,7 @@ impl Solution for Day10 {
             self.run(1);
             height = self.height();
         }
-        format!("{}", steps - 1)
+        (steps - 1).to_string()
     }
 }
 

2018/src/day12.rs

@@ -110,7 +110,7 @@ impl Solution for Day12 {
         let mut state = self.read_input(input);
         state = self.simulate_n(state, 20);
 
-        format!("{}", self.sum(&state))
+        self.sum(&state).to_string()
     }
 
     fn part2(&mut self, input: &mut Read) -> String {

2018/src/day14.rs

@@ -87,7 +87,7 @@ impl Solution for Day14 {
         input.read_to_string(&mut buf).unwrap();
 
         let input = buf.trim().parse().unwrap();
-        format!("{}", find_first(input, buf.trim().len()))
+        find_first(input, buf.trim().len()).to_string()
     }
 }
 

2018/src/day15.rs

@@ -194,7 +194,7 @@ impl Day15 {
     fn return_score(&self, rounds: usize) -> String {
         let result: usize = rounds * self.units.iter().map(|x| x.hp as usize)
             .sum::<usize>();
-        format!("{}", result)
+        result.to_string()
     }
 
     fn set_elf_power(&mut self, power: u8) {

2018/src/day16.rs

@@ -126,7 +126,7 @@ impl Solution for Day16 {
                 counter += 1;
             }
         }
-        format!("{}", counter)
+        counter.to_string()
     }
 
     fn part2(&mut self, input: &mut Read) -> String {
@@ -145,7 +145,7 @@ impl Solution for Day16 {
             cpu.execute(mapping[op[0] as usize], &op[1..4]).unwrap();
         }
 
-        format!("{}", cpu.registers[0])
+        cpu.registers[0].to_string()
     }
 }
 

2018/src/day17.rs

@@ -121,7 +121,7 @@ impl Solution for Day17 {
 
         let result = self.contained.len()
             + self.flowing.len() - self.ymin;
-        format!("{}", result)
+        result.to_string()
     }
 
     fn part2(&mut self, input: &mut Read) -> String {
@@ -129,7 +129,7 @@ impl Solution for Day17 {
 
         self.descend((500, 0));
 
-        format!("{}", self.contained.len())
+        self.contained.len().to_string()
     }
 }
 

2018/src/day18.rs

@@ -133,7 +133,7 @@ impl Day18 {
             .flat_map(|x| x.iter())
             .cloned().grouping_count();
 
-        format!("{}", result[&Tile::Tree] * result[&Tile::Lumber])
+        (result[&Tile::Tree] * result[&Tile::Lumber]).to_string()
     }
 }
 

2018/src/day19.rs

@@ -50,7 +50,7 @@ impl Solution for Day19 {
             cpu.registers[self.ip] += 1;
         }
 
-        format!("{}", cpu.registers[0])
+        cpu.registers[0].to_string()
     }
 
     fn part2(&mut self, input: &mut Read) -> String {
@@ -73,7 +73,7 @@ impl Solution for Day19 {
             cpu.registers[self.ip] += 1;
         }
 
-        format!("{}", cpu.registers[0])
+        cpu.registers[0].to_string()
     }
 }
 

2018/src/day20.rs

@@ -138,7 +138,7 @@ impl Solution for Day20 {
         let pos = (0, 0);
 
         self.follow_directions(&[pos], &data[1..]);
-        format!("{}", self.distances().values().max().unwrap())
+        self.distances().values().max().unwrap().to_string()
     }
 
     fn part2(&mut self, input: &mut Read) -> String {
@@ -147,7 +147,7 @@ impl Solution for Day20 {
         let pos = (0, 0);
 
         self.follow_directions(&[pos], &data[1..]);
-        format!("{}", self.distances().values().filter(|&&x| x >= 1000).count())
+        self.distances().values().filter(|&&x| x >= 1000).count().to_string()
     }
 }
 

2018/src/day21.rs

@@ -52,17 +52,17 @@ impl Day21 {
 
 impl Solution for Day21 {
     fn part1(&mut self, _input: &mut Read) -> String {
-        format!("{}", ValidInputs::new(0).next().unwrap())
+        ValidInputs::new(0).next().unwrap().to_string()
     }
 
     fn part2(&mut self, _input: &mut Read) -> String {
         let inputs = ValidInputs::new(0);
         let mut seen = HashSet::new();
-        let mut last = None;
+        let mut last: Option<i64> = None;
 
         for input in inputs {
             if seen.contains(&input) {
-                return format!("{}", last.unwrap());
+                return last.unwrap().to_string();
             } else {
                 last = Some(input);
                 seen.insert(input);

2018/src/day22.rs

@@ -95,7 +95,7 @@ impl Solution for Day22 {
 
         let result: usize = table.iter().flat_map(|x| x.iter())
             .sum();
-        format!("{}", result)
+        result.to_string()
     }
 
     fn part2(&mut self, input: &mut Read) -> String {
@@ -115,7 +115,7 @@ impl Solution for Day22 {
             }
             visited.insert(state);
             if state == target_state {
-                return format!("{}", dist);
+                return dist.to_string();
             }
 
             let (x, y) = state.pos;