From e9d90c396de3ee0d4c43ffe6938ec841305595c6 Mon Sep 17 00:00:00 2001
From: Eat-Swap <root@eatswap.org>
Date: Wed, 18 May 2022 22:11:58 +0800
Subject: [PATCH] add: 220518 [cpp]

---
 cpp/2205/220518.cpp     | 49 +++++++++++++++++++++++++++++++++++++++++
 cpp/2205/CMakeLists.txt |  2 +-
 2 files changed, 50 insertions(+), 1 deletion(-)
 create mode 100644 cpp/2205/220518.cpp

diff --git a/cpp/2205/220518.cpp b/cpp/2205/220518.cpp
new file mode 100644
index 0000000..348f12e
--- /dev/null
+++ b/cpp/2205/220518.cpp
@@ -0,0 +1,49 @@
+#include <vector>
+#include <functional>
+
+class Solution {
+public:
+	static std::vector<std::vector<int>> criticalConnections(int n, const std::vector<std::vector<int>>& e) {
+		auto* G = new std::vector<int>[n];
+		for (const std::vector<int>& i : e) {
+			G[i[0]].push_back(i[1]);
+			G[i[1]].push_back(i[0]);
+		}
+
+		std::vector<int> preTS(n);
+		int dfsTS = 0;
+		std::vector<std::vector<int>> ret;
+		std::function<int(int, int)> dfs = [&](int u, int prevE) {
+			int low_u = preTS[u] = ++dfsTS;
+
+			int chCnt = 0;
+			for (int v : G[u]) {
+				if (v == prevE)
+					continue;
+				if (preTS[v] && preTS[v] < preTS[u]) {
+					low_u = std::min(low_u, preTS[v]);
+				} else if (!preTS[v]) {
+					++chCnt;
+					int low_v = dfs(v, u);
+					low_u = std::min(low_u, low_v);
+					if (low_v > preTS[u]) {
+						// u is an articulation vertex
+						// (u, v) is a bridge
+						ret.push_back({u, v});
+					}
+				}
+			}
+			return low_u;
+		};
+		dfs(0, -1);
+
+		delete[] G;
+		return ret;
+	}
+};
+
+int main() {
+	auto r = Solution::criticalConnections(5, {{1,0},{2,0},{3,2},{4,2},{4,3},{3,0},{4,0}});
+
+	return 0;
+}
diff --git a/cpp/2205/CMakeLists.txt b/cpp/2205/CMakeLists.txt
index 730f500..e92713e 100644
--- a/cpp/2205/CMakeLists.txt
+++ b/cpp/2205/CMakeLists.txt
@@ -3,4 +3,4 @@ PROJECT(2205)
 
 SET(CMAKE_CXX_STANDARD 23)
 
-ADD_EXECUTABLE(2205 220517-CN.cpp 220517.cpp)
+ADD_EXECUTABLE(2205 220518.cpp)