AoC 2021, day 10.

Author: pin3da

2021/day10/Cargo.lock

@@ -0,0 +1,8 @@
+[package]
+name = "day10"
+version = "0.1.0"
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

2021/day10/Cargo.toml

@@ -0,0 +1,10 @@
+[({(<(())[]>[[{[]{<()<>>
+[(()[<>])]({[<{<<[]>>(
+{([(<{}[<>[]}>{[]{[(<()>
+(((({<>}<{<{<>}{[]{[]{}
+[[<[([]))<([[{}[[()]]]
+[{[{({}]{}}([{[{{{}}([]
+{<[[]]>}<{[{[{[]{()[[[]
+[<(<(<(<{}))><([]([]()
+<{([([[(<>()){}]>(<<{{
+<{([{{}}[<[[[<>{}]]]>[]]

2021/day10/src/example.txt

@@ -0,0 +1,94 @@
+[{<<<{{[(<{{{{[]()}{[]()}}<[[]<>]<[]()>>}([[[][]]]<[{}<>]((){})>)}>)[<([<<(){}>{(){}}>[[<>{}](<>[
+<<{(<({[<{{<[<()()><{}{}>][[()[]][(){}]]>((<[]<>>(<>{}))((<>{}){<>()}))}<{({{}}[<>{}])({{}{}}{{}
+(<[(<<[((({<[{()[]}]>}{[[[{}[]]{{}{}}][{{}()}<<>()>]]})))<[([(<[{}{}]>{<<>{}>})<((<>()){[][]})<{<
+{({<[[[(<{{<<[[]()]>]}{<({<>{}}([]<>))[({}{}){()()}]>((<[][]>{[]()})[(()<>)[{}{}]])}}>){[<[{[{[]}{<><>
+(<{([(<[{[{<[<()<>>({}[])]>}][<{({<>}(<><>))}({[<>{}](<>())}{[{}()]<()<>>})><[<<{}<>><()[])>[<{}[]
+{<{[({<<<[[<(({}))>(([<><>][<><>])<<()()][{}{}]>)]][<[{<{}{}>(<>[])}](({{}[]}(()()))<<[]()>
+(<{[[(({(<([([[]{}][()[]]){{()[]}[<><>]}](<(<><>){[][]}>({{}{}}{{}()})))>){((([{()}[{}[]]]))[<[
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+{({[([{(<{{(<[<>[]]<[]<>>>(<{}[]>[<>[]]))<([{}<>]{{}()})<[()()]([]{})>>}(<{<<>{}>([][])}><(({}[])
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+{[[<<{<({<[(([{}]<<>[]>))[<{<><>}({}{})>]]{([{()<>}{[]()}][{()()}<(){}>])(<({}{})<[]{}>>[[<>{}]
+{<[({{{[(<(({{()<>}(()[])}[<<>{}>{{}<>}])<{({}[])<()()>}{(()())<{}()>}>}([<(()())([][])>[([]){()<>}]]
+[{<[{{(([{{<({<>[]}(<>()))<[[][]]>>(([{}]({}())){[()[]]((){})})}{((<<>[]>[[]<>])<[<>[]}([]())>)
+[<<<{[((({<[((()<>)<()[]>){{<>{}}({}())}]{{<[]()>[[]()]}{[()]<{}[]>}}>[[{[<>()]}((<><>><()<>>)](([[]()](()))[
+(([<<{<[<[({{<()<>><[]{}>}{{()()><<><>>}})<[[{(){}}[[][]]][[[]<>]]]{{((){})}[[<>{}]<[][]>]}>][[({({})[[]
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+{<{(([(([{{{({<>}({}{}))[[[][]]([]<>)]}<<(()[])[[]]>((<><>)<[][]>)>}}[[[(<[]{}>)]{{([]()){{}<>}>[<[
+([[[{[([{{<{<<()()>(()[])>{({}()){<>[]}}}><(((()())({}[]))([()[]]<<>[]>))[[{{}[]>]{((){})}]>}<[[[[
+{[[[{(<[{(({<<{}()>{<>{}}>[[[]()]<{}{}>]}{[[{}[]]{{}}]((<>))}))[{{{(()[])<{}{}>}<<[][]>{<>()}>}{[{<>{}}<(){}>
+<({[<[(<<{[{<{{}<>}(()())>(<(){}>[<><>])}[([{}]{()[]})<{<>{}}{{}}>]]<{([()[]]<()[]>)[([]())([]<>)]}((((){}
+{[<<[{([((([(({})[{}<>])({[]()}{<>{}})][{{{}<>}}(({}<>))]){<{<<>()>[(){}]}(({}<>)<<>[]>)>[<[()[]]([][])
+<<([<<{[<<<<<(<>{})<{}{}>>>{([()()]<<><>>)(((){}))}>{<<[[]<>][(){}]>[(()<>){[][]}]>{(<()()){<>{}})<[[]{}
+[{<{[{{([<({({(){}}<{}<>>){[{}{}]{()<>}}}[{<{}[]><<>[]>}<[[]()][{}<>]>])<{([{}[]][<>[]])<[<>()](()[])>}[(<
+({([{{<[[[({<(<>())<<>()>>([()[]](<><>))}{<(<>[])<{}()>>({{}[]}{{}<>})})[<{[[][]]({}[])}{{{}[]}}
+{<[([{<[[<([{<[]<>>(()<>)}[(<>{})<{}{}>]][({<><>}<[]()>)(<()()>[{}{}])])>]]<[[({([<><>]{()})<{<>()}{<>
+[(<[[{[{{{<({[()()][[]<>]}<(<>[]){[]{}}>)<[{()()}{[]}]<[{}{}]<{}[]>>>>}{([<[()[]]>{([][]){()[]}}])}}}]<{<[
+{{<{<((<<{[<{[<>()]<<>[]>}<<[]()><{}()>>>({(<>[])<<><>>}{(<>[])(()())})]}>[[[[{<[]()>[()[]]}((<>{})[()<>])
+[<<[<[{(<({{[{[]<>}<{}()>][[<>[]][{}<>]]}<(({}{})({}[]))({[]<>}[{}{}])>}<[(<[]{}>[()()])][[({}[])(()
+<{[{[<<(<{([{({}{}){<>{}}}{[()](()<>)}][[({}())({}<>)][<()<>>{<><>}]])}<({{((){})(()[])}}(<[{}[]]<[][]>><{
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+[(<[{<({{<<<<{<>{}}(<><>)>[{[][]}[[][]]]>{([(){}](<><>))((()<>))}><<{{{}<>}{{}<>}}({<>}<[]<>>)>>>{{{(([])[{}{
+((({[[[[<<<{<<[][]><<>()>>[<()[]>(()<>)]}{{<<>{}><<>[]>}{[{}{}][()()]}}><{[[{}[]]<{}[])]{{<>[]}
+[({[[<<<<{[<(<[]<>>[<>()])[[<><>]<<>()>]>>{[{(<><>)[()()]}{(()())[<>{}]}]{{<<><>><[][]>}({<>[]}(()<>
+{[[{(<<([[{(<[{}]>{{<>{}}{{}[]}})}]{<({[(){}][()()]}{(<>{})[[]]})>{<{[[]()][<>[]]}(<[]()>[<>{}]]><{[{}()
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+<(((<(<<<[[[<{[][]}>{<[]>{<>[]}]]{<<{}[]>[()()]>}]([([()()]<[]()>){{{}()}}]<(({}{})(()()))
+[{{<[{[<<<[[<<{}<>>({}<>)>[<[]()>(()())>]<<<()[]><[][]>><[[]{}]([]{})>>]>><[{(<([])<{}()>>(<{}<>><<>{}>)
+<<<(<[[[<(<<[[[][]][{}{}]]>>(<([[]()))({{}[]}[[][]])>))><[{(<({}<>)(()<>)>{[{}<>]})[({<><>}[<>()])<
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+(<{(<([([{({{{[][]}{[]<>}}[<{}[]>[<>[]]]})}(<[{{(){}}(<><>)}((()[]))](([{}()]([])){([]<>]{{}()}})>[[[{(
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+<<{([[[<((<{{(<>[])[()[]]}([[]()])}>))>]]]<<({[(({<{[][]}({}[])>{<{}{}>[<>{}]}}<<[<>()][[]()]>{
+<[[({([<[<{([{[][]}[<><>]]{([]<>)(()<>)})[<(()())<[]<>>>[<[]<>>(()())]]}>(<(<[[]()]<[][]>>{[[]()]{[][]}}
+[<([[({[{{<{{([][])}(<<><>>(()<>))}[[<{}{}>{{}[]}]{{[]{}}}]>}}[<<[{({}{}){{}()}}({[]{}}([]{}))][{[()()]
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2021/day10/src/input.txt

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+use std::collections::VecDeque;
+
+type Chunk = VecDeque<char>;
+type Input = Vec<Chunk>;
+
+fn main() {
+    let example = parse_input(include_str!("example.txt"));
+    let input = parse_input(include_str!("input.txt"));
+    solve(&example);
+    solve(&input);
+}
+
+fn parse_input(s: &str) -> Input {
+    s.lines().map(|it| it.chars().collect()).collect()
+}
+
+fn solve(input: &Input) {
+    let part1: Vec<(&Chunk, i32)> = input.iter().map(cost_first_error).collect();
+    println!("Part 1: {}", part1.iter().map(|i| i.1).sum::<i32>());
+    let mut part2: Vec<i64> = part1
+        .iter()
+        .filter(|i| i.1 == 0)
+        .map(|it| it.0)
+        .map(cost_fixing)
+        .collect();
+    part2.sort();
+    println!("Part 2: {:?}", part2[part2.len() / 2]);
+}
+
+fn cost_first_error(input: &Chunk) -> (&Chunk, i32) {
+    let mut matched = Chunk::new();
+    for i in input {
+        match i {
+            '{' | '(' | '[' | '<' => matched.push_back(*i),
+            _ => {
+                if matched.pop_back().unwrap_or('#') != matching(i) {
+                    return (input, cost(i).unwrap());
+                }
+            }
+        }
+    }
+
+    return (input, 0);
+}
+
+fn cost_fixing(input: &Chunk) -> i64 {
+    let mut matched = Chunk::new();
+    for i in input {
+        match i {
+            '{' | '(' | '[' | '<' => matched.push_back(*i),
+            _ => {
+                assert!(matched.pop_back().unwrap_or('#') == matching(i));
+            }
+        }
+    }
+    let mut score: i64 = 0;
+    while matched.len() > 0 {
+        let cur = cost(&matched.pop_back().unwrap()).unwrap();
+        score *= 5;
+        score += cur as i64;
+    }
+    return score;
+}
+
+fn cost(c: &char) -> Result<i32, &str> {
+    match c {
+        ')' => Ok(3),
+        ']' => Ok(57),
+        '}' => Ok(1197),
+        '>' => Ok(25137),
+        // cost of adding matching pair.
+        '(' => Ok(1),
+        '[' => Ok(2),
+        '{' => Ok(3),
+        '<' => Ok(4),
+        _ => Err("invalid char"),
+    }
+}
+
+fn matching(c: &char) -> char {
+    match c {
+        ')' => '(',
+        ']' => '[',
+        '}' => '{',
+        '>' => '<',
+        _ => 'x',
+    }
+}