5 files changed, 194 insertions, 0 deletions
diff --git a/2021/day10/day10 b/2021/day10/day10
new file mode 100755
index 0000000..e3b93c6
--- /dev/null
+++ b/2021/day10/day10
diff --git a/2021/day10/day10.cpp b/2021/day10/day10.cpp
new file mode 100644
index 0000000..4fad4ca
--- /dev/null
+++ b/2021/day10/day10.cpp
@@ -0,0 +1,88 @@
+#include <iostream>
+#include <fstream>
+#include <vector>
+#include <stack>
+#include <string>
+#include <algorithm>
+
+#include "../utils.h"
+
+char map (char a) {
+	if (a == '(') return ')';
+	if (a == '[') return ']';
+	if (a == '{') return '}';
+	if (a == '<') return '>';
+	return 'A';
+}
+
+bool match (char a, char b) {
+	if (a == '(' && b == ')') return true;
+	if (a == '[' && b == ']') return true;
+	if (a == '{' && b == '}') return true;
+	if (a == '<' && b == '>') return true;
+	return false;
+}
+
+int score (char a) {
+	if (a == ')') return 3;
+	if (a == ']') return 57;
+	if (a == '}') return 1197;
+	if (a == '>') return 25137;
+	return 0;
+}
+
+long score (std::string str) {
+	long s = 0;
+	for (char c : str) {
+		s *= 5;
+		s += (c == ')' ? 1 : 0);
+		s += (c == ']' ? 2 : 0);
+		s += (c == '}' ? 3 : 0);
+		s += (c == '>' ? 4 : 0);
+	}
+	return s;
+}
+
+bool check (std::string line, std::string &out) {
+	std::stack<char> stack;
+	for (char c : line) {
+		if (c == '(' || c == '[' || c == '{' || c == '<') {
+			stack.push(c);
+		} else {
+			if (!match(stack.top(), c)) {
+				out.push_back(c);
+				return true;
+			} else stack.pop();
+		}
+	}
+	while (!stack.empty()) {
+		out.push_back(map(stack.top()));
+		stack.pop();
+	}
+	return false;
+}
+
+int main (int argc, char *argv[]) {
+	std::string raw;
+	std::getline(std::ifstream(argv[1]), raw, '\0');
+	std::vector<std::string> lines;
+	split(lines, raw, "\n");
+
+	std::vector<long> repairs;
+	int sum = 0;
+	for (auto line : lines) {
+		if (line.size() == 0) continue;
+		std::string rep;
+		bool corrupt = check(line, rep);
+		if (corrupt) sum += score(rep[0]);
+		else {
+			repairs.push_back(score(rep));
+			std::cout << score(rep) << " " << rep << std::endl;
+		}
+	}
+	std::cout << "corrupt score: " << sum << std::endl;
+	std::sort(std::begin(repairs), std::end(repairs));
+	std::cout << "repairs score: " << repairs[(repairs.size()-1)/2] << std::endl;
+
+	return 0;
+}
diff --git a/2021/day10/day10_input.txt b/2021/day10/day10_input.txt
new file mode 100644
index 0000000..eec53e5
--- /dev/null
+++ b/2021/day10/day10_input.txt
@@ -0,0 +1,94 @@
+({<{({([<<{<[<<><>><<>>](<()()>)><{{{}<>}}<<<>{}>[<>[]]>>}{[<<[]{}>[<>()]>[(()[])]]<{{<><>}[[]<>]}{<
+[(<[[([[(([<{{[]{}}([][])}<<{}[]>([]{})>><{<()()><[][]>}{[()]<()[]>}>]<{({()()}){[{}[]][<>()]}}[{[{}<>]
+{{(<[[(<<<(<<[{}{}]{<>()}><{[]{}}([]{})>>([([][]){{}<>}][<()<>>[(){}]]))<{<(<>())[{}<>]>{{[]{}}<<>{}>}}({<
+<([({[<[(([[<(()<>){[]<>}><<(){}>{()()}>]](<(({}[]){[][]})<{<>())[<>[]]>>{{{()<>}{(){}}}{[<>()]<{}[]>}
+<(((<{<(<{{[[[()<>]{[]()}]][{<()[]><<>{}>}]}}[<{[{[][]}[<><>]]}{{{(){}}[<>()]}{[[]()]{<>[]}}}>{[({{}
+{{({[({(({{[<[{}()]([]<>)><<{}()>[<>[]]>]<<{[]{}}([]<>)>{{<>}{<>{}}}}}{{<<[]<>>{<>()}>}<({[]<>}
+(([{[(<(<[[(([()[]][{}()])(([][])<{}<>>))]]>)[<(<{{<<><>>(<>[])}<([]<>)[[]{}]>}((<{}[]>[<><>]){{[
+{{[<<{<<(<([<<[]()>[[][]]>{[()[]]<()[]>}]){(<(<>{})([])>{<(){}>{<>()]}){[<[]()><<>()>](([][
+((<{[{{(<<[(<{<>{}}[<>[]]>{<{}<>>{{}[]}})]>><{([<(<>())[{}()]>{<<>{}>{[]{}}}><([[]()]<[]<>>)(<[]>{()()})>)}>)
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+([(<<<(<(([([{<>{}}<(){}>](<{}<>>[{}{}]})][([<()>{{}[]}](<<>()><()[]>))[[{<>()}[<>[]]]{<<>[]>
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+{[([([<[(<<[<[[]()]<[]<>>>][{<[][]>[<>()]}{({}<>)<()[]>}]><{({<>()}{<><>})<{(){}}({}{})>}<{(
+<<({[<<{(<[<({{}[]}{<>[]})[<()()>]>(([<>()][<><>])(<<>{}><()[]>))](<[<{}<>>[{}[]]]({{}{}}(
+[<<{<(([<[{(([()<>]({}{})){<<>[]>[()()]})({([])(<>())}[{[][]}[{}[]]])}{({(()())[()[]]}({[]<>}([][])))
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+[((<[{[[([{[[<<>>{<>()}]<[[]{}]<[]<>>>]}<({(()<>))<<<>()><<>[]>>)<{<[]{}>((){})}[({}[]){()()}]>
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diff --git a/2021/day10/day10_input_ez.txt b/2021/day10/day10_input_ez.txt
new file mode 100644
index 0000000..b1518d9
--- /dev/null
+++ b/2021/day10/day10_input_ez.txt
@@ -0,0 +1,10 @@
+[({(<(())[]>[[{[]{<()<>>
+[(()[<>])]({[<{<<[]>>(
+{([(<{}[<>[]}>{[]{[(<()>
+(((({<>}<{<{<>}{[]{[]{}
+[[<[([]))<([[{}[[()]]]
+[{[{({}]{}}([{[{{{}}([]
+{<[[]]>}<{[{[{[]{()[[[]
+[<(<(<(<{}))><([]([]()
+<{([([[(<>()){}]>(<<{{
+<{([{{}}[<[[[<>{}]]]>[]]
diff --git a/2021/day10/makefile b/2021/day10/makefile
new file mode 100644
index 0000000..038dc5d
--- /dev/null
+++ b/2021/day10/makefile
@@ -0,0 +1,2 @@
+all day10.cpp:
+	g++ -std=c++20 -o day10 day10.cpp