diff --git a/aoc2021.test/DayTests.cs b/aoc2021.test/DayTests.cs
index 7186a13..51cee5a 100644
--- a/aoc2021.test/DayTests.cs
+++ b/aoc2021.test/DayTests.cs
@@ -13,6 +13,7 @@ public class DayTests
[DataRow(typeof(Day07), "345035", "97038163")]
[DataRow(typeof(Day08), "362", "1020159")]
[DataRow(typeof(Day09), "478", "1327014")]
+ [DataRow(typeof(Day10), "288291", "")]
public void CheckAllDays(Type dayType, string part1, string part2)
{
var s = Stopwatch.StartNew();
@@ -52,6 +53,7 @@ public class DayTests
[DataRow(typeof(Day07), "37", "168")]
[DataRow(typeof(Day08), "26", "61229")]
[DataRow(typeof(Day09), "15", "1134")]
+ [DataRow(typeof(Day10), "26397", "288957")]
public void CheckTestInputs(Type dayType, string part1, string part2)
{
Day.UseTestInput = true;
diff --git a/aoc2021/Day10.cs b/aoc2021/Day10.cs
new file mode 100644
index 0000000..4907a80
--- /dev/null
+++ b/aoc2021/Day10.cs
@@ -0,0 +1,63 @@
+using System.Collections;
+
+namespace aoc2021;
+
+///
+/// Day 10:
+///
+public sealed class Day10 : Day
+{
+ private readonly List _input;
+ private readonly char[] _openers = { '(', '[', '{', '<' };
+ private readonly char[] _closers = { ')', ']', '}', '>' };
+
+ private readonly Dictionary _scores = new()
+ {
+ { ')', 3 },
+ { ']', 57 },
+ { '}', 1197 },
+ { '>', 25137 }
+ };
+
+ private readonly Dictionary _scoresClosing = new()
+ {
+ { '(', 1 },
+ { '[', 2 },
+ { '{', 3 },
+ { '<', 4 }
+ };
+
+ public Day10() : base(10, "Syntax Scoring")
+ {
+ _input = Input.ToList();
+ }
+
+ public override string Part1()
+ {
+ var s = new Stack();
+ var score = 0;
+ foreach (var line in _input)
+ {
+ foreach (var c in line)
+ {
+ if (_openers.Contains(c))
+ {
+ s.Push(c);
+ }
+ else
+ {
+ var y = s.Pop();
+ if (Math.Abs(y - c) <= 3) continue;
+ score += _scores[c];
+ break;
+ }
+ }
+ }
+
+ return score.ToString();
+ }
+
+ public override string Part2()
+ {
+ }
+}
diff --git a/aoc2021/input/day10.in b/aoc2021/input/day10.in
new file mode 100644
index 0000000..27355e5
--- /dev/null
+++ b/aoc2021/input/day10.in
@@ -0,0 +1,102 @@
+[<[{<[(([<[[{[()()]}]{<<<>[]>[()[]]>{(<>[]){<>[]}}}]<{(<()<>>{()<>})(<()>)}([{()[]}](<()<>>
+<[(<({[<(<<({({}[])[<>]}[<<>{}>[()()]])>>)>]})>{[([({[{{<[[]{}]{{}}><{()[]}[{}]>}}{{[<<>()>((){})
+{<({([<([[<<[(<>())({}{})](<()()>{{}})>(([[]{}]<[][]>){<{}>{<>{}}})>]][[((<[<>()]<<>[]>>{{()[]}{[]{}
+([{({<<{<<<{([{}[]]([]())){[(){}]}}{[<{}()>(<>[])]}][({[()<>][<><>]}{{{}[]}})<<<{}()>>>]>([[<[{}<>]
+{([{({(<{[<(<(()()){{}()}>[(<><>)<<>[]>])[{{{}()}[(){}]}[<()[]>[{}[])]]>{([{{}{}}{[]}][{{}<>}{<><>}]){[[[]()
+[{(([[{([(({(<{}()>({}<>))((()())(<>[]))}{<{{}[]}[{}()]>{{()()})})<{{([]{})[<>[]]}[{<>[]}{
+<<([{{({{{[(<[<>()][()<>]>)]}<(<<<<>()><{}()>>><({{}<>}{()[]}){<(){}>}>)>>})<[{[<([[{}{}]{{}()}]
+<[{{[<[{(<<([([]{})]<[[]{}]{<>()}>)(<<<>{}>{{}[]]>(<[]()>(()[])))><<[{[][]}{[]}](([])([]))><({{}{}}{[][]})
+{{{({{{([<<<{[()]({}{})}((()[])<()<>>)>{{<{}<>><{}()>}}>(<<(())({}())>{{{}}({}())}>{<[{}<>]<{}{}>>[{<>()}
+{<({<[{[<<{{[[[][]][<><>]](([]{})<()[]>)}<<((){})><[[][]](<><>)>>}{(<<{}<>><<>>><((){})([]<>)>)<(([]))(
+({{{([({<((<<<()>[[]<>]>(<<><>>(()()))>))>})]){({[<[<<[[{}{}]][([]<>)]><{<{}()><()<>>}(<[][]>[{}()])]>{({{
+(<{<<[[[(<{<({<>()}{{}<>})<<()()>(<>[])>>(({{}()}([])))}>([[<({}())({}())]((<>{})<<><>>)][[<(
+[([({{{[<([<[(<>[])[{}[]]]<[[]{}][<>]>>])<(((<()<>>(<>{}])({<>{}}[{}<>]))<([()()]{[]<>})({<>()}[{}
+<(<<([{{[<((({<><>}<<>>)[[[]<>]({}())]){(<<>()>{[]()})[<()>{[][]}]})>]<[[[{(<>{})<(){}>}[{<>{}}]]]][
+{[[[{[(((<{[{([]{})[[][]]}(<{}()><<>[]>)][<[<>{}]>]}>({([(()())<[]{}>](([]{})[<>{}])][[{[]{}}<<>{}>]({{}}[<>
+{{{([[<[({<<<({}{})<[]()>>[[<>[]>{<>[]}]>[({<>[]}({}<>))[[[]()][()<>]]]>})]>]<(<<<<[<((){})<{}{}>><{()()}((
+[{<<<[((<{{{[<{}{}>[{}{}]]([{}<>]{{}<>})}{{[{}{}][{}]}({[]<>}{<><>})}][([<[]<>><{}<>>][<(){}>(()
+[{<(<[{(<(<((((){})<[]<>>)[{()<>}{[]<>}])><(((<>)(<>[]))(<[]<>>))([<<><>>[[]<>]]{<[]()>{()[]}})>){<({{[][
+<(<<<[([[<{{(({}[])[<>{}])<(()<>)({}{})>}}>{{([(<>())<()[]>]{{[]<>}})<[[<>()]](<()[]>)>}<{[<{}<>><{}[]>](
+{((<[<[<(<[({{{}<>}(()<>)}{(<>{})[[]{}]})(((()[])))]>)[{([([<><>][{}[]])[<()[]>(<>[])]]({[
+[({([<([({<(<<(){}><{}<>>>{{<>[]}[()[]]})[[[{}[]](()())]]]({[{(){}}{()}]<{{}()}{{}()}>}[([[][]][()[
+({[[{[[({{[[(<<><>>{()}){[()()]}]<{{<><>}({}())}{{[][]}{()()>}>]<[{<<>[]>[[]<>]}]<[<()[]><(
+(<[{[(<{(<{{[{<><>}{[][]}](<(){}><[]()>)}}><{<(<<>()>([]<>))<({}<>){{}()}>>}{([(()[]}[<>[]]])<{{[]{}}
+<{{(<([(<<<<[{{}<>}(()[])][<{}[]>[<>[]]]><<{[]()}(()<>)>({()<>}({}[]))>><[(([]{}))[{<><>}([][])]]{{(<>())}(
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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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+[[<[(((({[[[({<>{}}{{}()})[<(){}>{<>}]]{(<<>{}>(()<>))([[]<>]<()<>>)}](<([[]{}]<()()>)>{<[()
+[<<<[{[<{[(({([][]){<>}}))(<{([]())[{}()]}[[{}[]]{[]<>}]><{(<>())<[][]>}[([][]){{}()}]>)](
+<(<{<<[([[<{[[<>()]<{}{}>][[(){}]<<><>>]}>]{(([[<>[]](<>{})>{<()[]><[][]>})[<[(){}]{[][]}><[<>()]([][]
+<[([<<[{{[<<<{<>()}[<>()]>[<{}{}>[{}{}]]>[{[(){}]}([[]{}])]>]}}]>>{<([<(({({[][]}){([]()){{}{}}}}
+[({{{((<{<{[<<{}{}>><<[]{}><<>{}>>][<{{}()}>]}[(<[[]]<<>[]>>[([]())<<>{}>]){<[{}[]]>((()<>)[[]{}
+{[<[[(({([[<[(<>{})<<>{}>]{<()<>><{}[]>}>[[{{}<>}([]<>)][({}())([]())]]]])[[({{[[]<>][<>{}]}[[<>
+(((<[[<<{{[[[([]{})<{}<>>]]{{[<>[]]<{}{}>}({<><>}{()()})}][[<<[]()>{<>[]}><(()())<()[]>>]{{([](
+[<{<[[[<<{[{<({})([][])>[{[]()}]}<[{{}()}[<><>]]>][((<[]{}><{}()>)(<<>()>))([<<>()>((){})>)]}{[({(<>())<(
+{([<[{{{<[{[({<>()}(<>{})}[{()()}[<><>]]]}<{{{<>[]}[{}[]]}({[]()}[{}()])}<({()()}<<><>>){{{}{}}
+{{<[[<({([{(([[]<>][{}<>])){{({}{})<<>()>}}}[[{[<><>][{}{}]}<{[][]}([]())>]<<[()[]]{()<>}>{<{}[]}(()())}>]
+<({<[([{[[<{<{[]{}}[<>]>}>([(<()[]>[[]<>])<{<>[]}>]{[(()())[{}]][<{}<>><{}>]})]]([{{{([]{})[(){}]}[<
+[<<[{[{{[[{[[[()<>][()[]]](({}<>)[()<>])]<<(()[])>([<>[]]{()<>})>}([<[{}{}]>{({}<>){[][]}}][{[<>[]][<>]}])]]}
diff --git a/aoc2021/input/test10.in b/aoc2021/input/test10.in
new file mode 100644
index 0000000..4861500
--- /dev/null
+++ b/aoc2021/input/test10.in
@@ -0,0 +1,10 @@
+[({(<(())[]>[[{[]{<()<>>
+[(()[<>])]({[<{<<[]>>(
+{([(<{}[<>[]}>{[]{[(<()>
+(((({<>}<{<{<>}{[]{[]{}
+[[<[([]))<([[{}[[()]]]
+[{[{({}]{}}([{[{{{}}([]
+{<[[]]>}<{[{[{[]{()[[[]
+[<(<(<(<{}))><([]([]()
+<{([([[(<>()){}]>(<<{{
+<{([{{}}[<[[[<>{}]]]>[]]
\ No newline at end of file