From c82a6bcffc67552384e530aea1ecf9c0256e0281 Mon Sep 17 00:00:00 2001
From: eriedaberrie <eriedaberrie@gmail.com>
Date: Sun, 3 Dec 2023 21:49:21 -0800
Subject: [PATCH] 2023 day 4

---
 2023/4/main-1.cpp | 35 +++++++++++++++++++++++++++++++++
 2023/4/main-2.cpp | 49 +++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 84 insertions(+)
 create mode 100644 2023/4/main-1.cpp
 create mode 100644 2023/4/main-2.cpp

diff --git a/2023/4/main-1.cpp b/2023/4/main-1.cpp
new file mode 100644
index 0000000..246ae46
--- /dev/null
+++ b/2023/4/main-1.cpp
@@ -0,0 +1,35 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+int main() {
+	ios::sync_with_stdio(0);
+	cin.tie(0);
+
+	int ret = 0;
+
+	string line;
+	while (getline(cin, line) && !line.empty()) {
+		int count = 1;
+		int start = line.find(':');
+		int bar = line.find('|');
+		string left = line.substr(start + 2, bar - start - 3);
+		string right = line.substr(bar + 2);
+		istringstream lss(left), rss(right);
+		vector<int> rv;
+		while (!rss.eof()) {
+			int n;
+			rss >> n;
+			rv.push_back(n);
+		}
+		while (!lss.eof()) {
+			int n;
+			lss >> n;
+			for (auto no : rv) {
+				if (no == n)
+					count <<= 1;
+			}
+		}
+		ret += count >> 1;
+	}
+	cout << ret << '\n';
+}
diff --git a/2023/4/main-2.cpp b/2023/4/main-2.cpp
new file mode 100644
index 0000000..9d35fc8
--- /dev/null
+++ b/2023/4/main-2.cpp
@@ -0,0 +1,49 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+int main() {
+	ios::sync_with_stdio(0);
+	cin.tie(0);
+
+	int ret = 0;
+	vector<vector<int>> lefts, rights;
+	vector<int> copies;
+
+	string line;
+	while (getline(cin, line) && !line.empty()) {
+		copies.push_back(1);
+		int start = line.find(':');
+		int bar = line.find('|');
+		string left = line.substr(start + 2, bar - start - 3);
+		string right = line.substr(bar + 2);
+		istringstream lss(left), rss(right);
+		vector<int> rv, lv;
+		while (!rss.eof()) {
+			int n;
+			rss >> n;
+			rv.push_back(n);
+		}
+		rights.push_back(rv);
+		while (!lss.eof()) {
+			int n;
+			lss >> n;
+			lv.push_back(n);
+		}
+		lefts.push_back(lv);
+	}
+	for (int cn = 0; cn < copies.size(); cn++) {
+		ret += copies[cn];
+		int n = cn;
+		for (int ln : lefts[cn]) {
+			for (int rn : rights[cn]) {
+				if (ln == rn) {
+					if (++n == copies.size())
+						goto end;
+					copies[n] += copies[cn];
+				}
+			}
+		}
+	end:;
+	}
+	cout << ret << '\n';
+}