6 files changed, 141 insertions, 1 deletions

diff --git a/2024/03/Makefile b/2024/03/Makefile
new file mode 100644
index 0000000..103a6a9
--- /dev/null
+++ b/2024/03/Makefile
@@ -0,0 +1,24 @@
+CC=g++ -std=c++20 -g -Wall
+
+a:
+        ${CC} -o a.out day03a.cpp
+
+b:
+        ${CC} -o b.out day03b.cpp
+
+clean:
+        rm -f a b
+
+atest: a
+        ./a.out
+
+btest: b
+        ./b.out
+
+arun: a
+        ./a.out < input
+
+brun: b
+        ./b.out < input
+
+.PHONY: a b clean atest btest arun brun
diff --git a/2024/03/b.out b/2024/03/b.out
new file mode 100755
index 0000000..49b7a0c
--- /dev/null
+++ b/2024/03/b.out
diff --git a/2024/03/day03a.cpp b/2024/03/day03a.cpp
new file mode 100644
index 0000000..2fb04cf
--- /dev/null
+++ b/2024/03/day03a.cpp
@@ -0,0 +1,48 @@
+#include <algorithm>
+#include <iostream>
+#include <sstream>
+#include <string>
+#include <string_view>
+#include <vector>
+using namespace std;
+
+int trymult(const string_view &s) {
+        if (s.substr(0, 4) != "mul(")
+                return 0;
+
+        auto t = s.substr(4, s.length()-4);
+
+        int x = 0, y = 0;
+        int i = 0;
+        for (; i < 3; i++)
+                if (t[i] >= '0' && t[i] <= '9')
+                        x = (x*10) + t[i]-'0';
+                else break;
+        if (i == 0 || t[i] != ',')
+                return 0;
+        i++;
+        int j = 0;
+        for (; j < 3; j++)
+                if (t[i+j] >= '0' && t[i+j] <= '9')
+                        y = (y*10) + t[i+j]-'0';
+                else break;
+        if (j == 0 || t[j+i] != ')')
+                return 0;
+        return x*y;
+}
+
+int mults(const string &line) {
+        int result = 0;
+        for (auto i = line.begin(); i != line.end(); i++)
+                result += trymult(string_view(i, line.end()));
+        return result;
+}
+
+int main() {
+        string line;
+        int result = 0;
+        while (cin >> line)
+                result += mults(line);
+        cout << result << endl;
+        return 0;
+}
diff --git a/2024/03/day03b.cpp b/2024/03/day03b.cpp
new file mode 100644
index 0000000..06c8f21
--- /dev/null
+++ b/2024/03/day03b.cpp
@@ -0,0 +1,63 @@
+#include <algorithm>
+#include <iostream>
+#include <sstream>
+#include <string>
+#include <string_view>
+#include <vector>
+using namespace std;
+
+bool state = true;
+
+int trymult(const string_view &s) {
+        if (s.substr(0, 4) != "mul(")
+                return 0;
+
+        auto t = s.substr(4, s.length()-4);
+
+        int x = 0, y = 0;
+        int i = 0;
+        for (; i < 3; i++)
+                if (t[i] >= '0' && t[i] <= '9')
+                        x = (x*10) + t[i]-'0';
+                else break;
+        if (i == 0 || t[i] != ',')
+                return 0;
+        i++;
+        int j = 0;
+        for (; j < 3; j++)
+                if (t[i+j] >= '0' && t[i+j] <= '9')
+                        y = (y*10) + t[i+j]-'0';
+                else break;
+        if (j == 0 || t[j+i] != ')')
+                return 0;
+
+        return x*y;
+}
+
+bool trytogglestate(bool current_state, const string_view &s) {
+        if (s.substr(0, 4) == "do()")
+                return true;
+        if (s.substr(0, 7) == "don't()")
+                return false;
+        return current_state;
+}
+
+int mults(const string &line) {
+        int result = 0;
+        for (auto i = line.begin(); i != line.end(); i++) {
+                string_view s(i, line.end());
+                state = trytogglestate(state, s);
+                if (state)
+                        result += trymult(s);
+        }
+        return result;
+}
+
+int main() {
+        string line;
+        int result = 0;
+        while (cin >> line)
+                result += mults(line);
+        cout << result << endl;
+        return 0;
+}
diff --git a/2024/learned.txt b/2024/learned.txt
index 56101dd..63a0a71 100644
--- a/2024/learned.txt
+++ b/2024/learned.txt
@@ -1,3 +1,5 @@
 List of things I learned (or refreshed) with this year's AoC.
 
 * Day 1: std::count()
+* Day 2: std::sstream
+* Day 3: std::string_view
diff --git a/2024/template.cpp b/2024/template.cpp
index 8428266..3707052 100644
--- a/2024/template.cpp
+++ b/2024/template.cpp
@@ -1,6 +1,9 @@
+#include <algorithm>
 #include <iostream>
+#include <sstream>
+#include <string>
+#include <string_view>
 #include <vector>
-#include <algorithm>
 using namespace std;
 
 int main() {