Day 7 2024

4 files changed, 109 insertions, 0 deletions

diff --git a/2024/07/Makefile b/2024/07/Makefile
new file mode 100644
index 0000000..63f62cd
--- /dev/null
+++ b/2024/07/Makefile
@@ -0,0 +1,24 @@
+CC=g++ -std=c++20 -g -Wall
+
+a:
+        ${CC} -o a.out day07a.cpp
+
+b:
+        ${CC} -o b.out day07b.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/2024/07/b.out b/2024/07/b.out
new file mode 100755
index 0000000..b512bd4
--- /dev/null
+++ b/2024/07/b.out
diff --git a/2024/07/day07a.cpp b/2024/07/day07a.cpp
new file mode 100644
index 0000000..3b56dea
--- /dev/null
+++ b/2024/07/day07a.cpp
@@ -0,0 +1,34 @@
+#include <algorithm>
+#include <iostream>
+#include <sstream>
+#include <string>
+#include <string_view>
+#include <vector>
+using namespace std;
+
+bool possible(long long x, vector<long long>& a, int i) {
+        if (i == 0)
+                return a[0] == x;
+        if (a[i] != 0 && x % a[i] == 0)
+                return possible(x/a[i], a, i-1) || possible(x-a[i], a, i-1);
+        return possible(x-a[i], a, i-1);
+}
+
+int main() {
+        string line;
+        long long tot = 0;
+        while (getline(cin, line)) {
+                long long x, i;
+                vector<long long> a;
+                stringstream s(line);
+                s >> x;
+                char colon;
+                s >> colon;
+                while (s >> i)
+                        a.push_back(i);
+                if (possible(x, a, a.size()-1))
+                        tot += x;
+        }
+        cout << tot << endl;
+        return 0;
+}
diff --git a/2024/07/day07b.cpp b/2024/07/day07b.cpp
new file mode 100644
index 0000000..1c2d900
--- /dev/null
+++ b/2024/07/day07b.cpp
@@ -0,0 +1,51 @@
+#include <algorithm>
+#include <iostream>
+#include <sstream>
+#include <string>
+#include <string_view>
+#include <vector>
+using namespace std;
+
+long long uncat(long long x, long long y) {
+        if (y == 0)
+                return x % 10 == 0 ? x / 10 : -1;
+        while (y > 0) {
+                if (x % 10 != y % 10)
+                        return -1;
+                x /= 10;
+                y /= 10;
+        }
+        return x;
+}
+
+bool possible(long long x, vector<long long>& a, int i) {
+        if (i == 0)
+                return a[0] == x;
+
+        bool p = possible(x-a[i], a, i-1);
+        if (a[i] != 0 && x % a[i] == 0)
+                p = p || possible(x/a[i], a, i-1);
+        auto u = uncat(x, a[i]);
+        if (u != -1)
+                p = p || possible(u, a, i-1);
+        return p;
+}
+
+int main() {
+        string line;
+        long long tot = 0;
+        while (getline(cin, line)) {
+                long long x, i;
+                vector<long long> a;
+                stringstream s(line);
+                s >> x;
+                char colon;
+                s >> colon;
+                while (s >> i)
+                        a.push_back(i);
+                if (possible(x, a, a.size()-1))
+                        tot += x;
+        }
+        cout << tot << endl;
+        return 0;
+}