From 79b905aea4bbe0c15c448f0af3f8cc733f763617 Mon Sep 17 00:00:00 2001
From: Sebastiano Tronto <sebastiano@tronto.net>
Date: Sat, 7 Dec 2024 07:51:09 +0100
Subject: Day 7 2024

---
 2024/07/Makefile   |  24 ++++++++++++++++++++++++
 2024/07/b.out      | Bin 0 -> 125104 bytes
 2024/07/day07a.cpp |  34 ++++++++++++++++++++++++++++++++++
 2024/07/day07b.cpp |  51 +++++++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 109 insertions(+)
 create mode 100644 2024/07/Makefile
 create mode 100755 2024/07/b.out
 create mode 100644 2024/07/day07a.cpp
 create mode 100644 2024/07/day07b.cpp

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
Binary files /dev/null and b/2024/07/b.out differ
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;
+}
-- 
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