30 files changed, 70 insertions, 33 deletions

diff --git a/.gitignore b/.gitignore
index afa46c7..df07bbc 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,3 @@
-bin/
-data/*.txt
+*/bin/
+*/data/*.txt
 .gdb_history
diff --git a/data/.gitkeep b/2020/data/.gitkeep
index e69de29..e69de29 100644
--- a/data/.gitkeep
+++ b/2020/data/.gitkeep
diff --git a/2020/src/day01.cpp b/2020/src/day01.cpp
new file mode 100644
index 0000000..d2d8629
--- /dev/null
+++ b/2020/src/day01.cpp
@@ -0,0 +1,55 @@
+#include <fstream>
+#include <functional>
+#include <iostream>
+#include <string>
+#include <vector>
+#include <numeric>
+using namespace std;
+
+auto
+read_file(string_view filename)
+{
+        fstream      input{ filename };
+        vector<long> data;
+
+        for ( long value = 0; input >> value; ) {
+                data.emplace_back(value);
+        }
+
+        return data;
+}
+
+void
+process(const vector<long>& values)
+{
+        const long year = 2020;
+
+        if (accumulate(values.begin(), values.end(), 0L) == year) {
+                cout << accumulate(values.begin(), values.end(), 1, multiplies<>()) << endl;
+        }
+}
+
+void
+combination(const vector<long>& values, size_t r)
+{
+        vector<bool> v(values.size());
+        fill(v.end() - long(r), v.end(), true);
+        vector<long> set(r);
+        do {
+                set.clear();
+                for ( size_t i = 0; i != values.size(); ++i ) {
+                        if ( v[i] ) {
+                                set.emplace_back(values[i]);
+                        }
+                }
+                process(set);
+        } while ( std::next_permutation(v.begin(), v.end()) );
+}
+
+int
+main()
+{
+        auto values = read_file("data/day01-sample1.txt");
+        combination(values, 2);
+        combination(values, 3);
+}
diff --git a/2023/data/.gitkeep b/2023/data/.gitkeep
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/2023/data/.gitkeep
diff --git a/src/day01.cpp b/2023/src/day01.cpp
index ff357bc..ff357bc 100644
--- a/src/day01.cpp
+++ b/2023/src/day01.cpp
diff --git a/src/day02.cpp b/2023/src/day02.cpp
index df560c3..aa3d5a2 100644
--- a/src/day02.cpp
+++ b/2023/src/day02.cpp
@@ -11,7 +11,7 @@ using namespace std;
 vector<string>
 split(const string& line, char sep)
 {
-        vector<string> parts{};
+        vector<string> parts;
         stringstream   input{ line };
 
         for ( string part; getline(input, part, sep); ) {
diff --git a/src/day03.cpp b/2023/src/day03.cpp
index b266f59..b266f59 100644
--- a/src/day03.cpp
+++ b/2023/src/day03.cpp
diff --git a/src/day04.cpp b/2023/src/day04.cpp
index 0d3e552..0d3e552 100644
--- a/src/day04.cpp
+++ b/2023/src/day04.cpp
diff --git a/src/day05.cpp b/2023/src/day05.cpp
index 42fda29..42fda29 100644
--- a/src/day05.cpp
+++ b/2023/src/day05.cpp
diff --git a/src/day06.cpp b/2023/src/day06.cpp
index 9a429c5..9a429c5 100644
--- a/src/day06.cpp
+++ b/2023/src/day06.cpp
diff --git a/src/day07.cpp b/2023/src/day07.cpp
index 1f44ac5..1f44ac5 100644
--- a/src/day07.cpp
+++ b/2023/src/day07.cpp
diff --git a/src/day08.cpp b/2023/src/day08.cpp
index 3e1b6c9..3e1b6c9 100644
--- a/src/day08.cpp
+++ b/2023/src/day08.cpp
diff --git a/src/day09.cpp b/2023/src/day09.cpp
index 4b30e6e..4b30e6e 100644
--- a/src/day09.cpp
+++ b/2023/src/day09.cpp
diff --git a/src/day10.cpp b/2023/src/day10.cpp
index 264e111..264e111 100644
--- a/src/day10.cpp
+++ b/2023/src/day10.cpp
diff --git a/src/day11.cpp b/2023/src/day11.cpp
index e1a0882..e1a0882 100644
--- a/src/day11.cpp
+++ b/2023/src/day11.cpp
diff --git a/src/day12.cpp b/2023/src/day12.cpp
index 11bd80b..11bd80b 100644
--- a/src/day12.cpp
+++ b/2023/src/day12.cpp
diff --git a/src/day13.cpp b/2023/src/day13.cpp
index 549457b..549457b 100644
--- a/src/day13.cpp
+++ b/2023/src/day13.cpp
diff --git a/src/day14.cpp b/2023/src/day14.cpp
index 8816ce1..8816ce1 100644
--- a/src/day14.cpp
+++ b/2023/src/day14.cpp
diff --git a/src/day15.cpp b/2023/src/day15.cpp
index 6fcbfc2..6fcbfc2 100644
--- a/src/day15.cpp
+++ b/2023/src/day15.cpp
diff --git a/src/day16.cpp b/2023/src/day16.cpp
index 93c7479..93c7479 100644
--- a/src/day16.cpp
+++ b/2023/src/day16.cpp
diff --git a/src/day17.cpp b/2023/src/day17.cpp
index 4098bba..4098bba 100644
--- a/src/day17.cpp
+++ b/2023/src/day17.cpp
diff --git a/src/day18.cpp b/2023/src/day18.cpp
index 3037739..3037739 100644
--- a/src/day18.cpp
+++ b/2023/src/day18.cpp
diff --git a/src/day19.cpp b/2023/src/day19.cpp
index a1d4eab..a1d4eab 100644
--- a/src/day19.cpp
+++ b/2023/src/day19.cpp
diff --git a/src/day20.cpp b/2023/src/day20.cpp
index f85ac90..f85ac90 100644
--- a/src/day20.cpp
+++ b/2023/src/day20.cpp
diff --git a/src/day21.cpp b/2023/src/day21.cpp
index c633155..c633155 100644
--- a/src/day21.cpp
+++ b/2023/src/day21.cpp
diff --git a/src/day22.cpp b/2023/src/day22.cpp
index 1afb994..1afb994 100644
--- a/src/day22.cpp
+++ b/2023/src/day22.cpp
diff --git a/src/day23.cpp b/2023/src/day23.cpp
index d8c20d3..d8c20d3 100644
--- a/src/day23.cpp
+++ b/2023/src/day23.cpp
diff --git a/src/day24.cpp b/2023/src/day24.cpp
index 76f459b..76f459b 100644
--- a/src/day24.cpp
+++ b/2023/src/day24.cpp
diff --git a/src/day25.cpp b/2023/src/day25.cpp
index 1d5e19e..1d5e19e 100644
--- a/src/day25.cpp
+++ b/2023/src/day25.cpp
diff --git a/makefile b/makefile
index 1849790..e1318c1 100644
--- a/makefile
+++ b/makefile
@@ -1,41 +1,23 @@
 include config.mk
 
-all: bin/day01 \
-         bin/day02 \
-         bin/day03 \
-         bin/day04 \
-         bin/day05 \
-         bin/day06 \
-         bin/day07 \
-         bin/day08 \
-         bin/day09 \
-         bin/day10 \
-         bin/day11 \
-         bin/day12 \
-         bin/day13 \
-         bin/day14 \
-         bin/day15 \
-         bin/day16 \
-         bin/day17 \
-         bin/day18 \
-         bin/day19 \
-         bin/day20 \
-         bin/day21 \
-         bin/day22 \
-         bin/day23 \
-         bin/day24 \
-         bin/day25
+all: $(patsubst 2020/src/%.cpp,2020/bin/%,$(wildcard 2020/src/*.cpp)) \
+        $(patsubst 2023/src/%.cpp,2023/bin/%,$(wildcard 2023/src/*.cpp))
 
-bin:
-        mkdir $@
+%/bin:
+        mkdir -p $@
 
-bin/%: src/%.cpp | bin
+# 2020
+2020/bin/%: 2020/src/%.cpp | 2020/bin
         c++ $(CPPFLAGS) $^ -o $@
 
-bin/day24: src/day24.cpp | bin
+# 2023
+2023/bin/%: 2023/src/%.cpp | 2023/bin
+        c++ $(CPPFLAGS) $^ -o $@
+
+2023/bin/day24: 2023/src/day24.cpp | 2023/bin
         c++ $(CPPFLAGS) -Wno-sign-conversion -I/usr/local/include $^ -L/usr/local/lib -lz3 -o $@
 
 clean:
-        rm -rf bin
+        rm -rf 2020/bin 2023/bin
 
 .PHONY: all clean