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/day07b.cpp | 51 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 51 insertions(+)
 create mode 100644 2024/07/day07b.cpp

(limited to '2024/07/day07b.cpp')

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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