add: 220429 [cpp]

cpp/2204/220429.cpp

@@ -0,0 +1,47 @@
+#include <vector>
+#include <queue>
+
+/**
+ * 785. Is Graph Bipartite?
+ * There is an undirected graph with n nodes, where each node is numbered between 0 and n - 1. You are given a 2D array graph, where graph[u] is an array of nodes that node u is adjacent to. More formally, for each v in graph[u], there is an undirected edge between node u and node v. The graph has the following properties:
+ * There are no self-edges (graph[u] does not contain u).
+ * There are no parallel edges (graph[u] does not contain duplicate values).
+ * If v is in graph[u], then u is in graph[v] (the graph is undirected).
+ * The graph may not be connected, meaning there may be two nodes u and v such that there is no path between them.
+ * A graph is bipartite if the nodes can be partitioned into two independent sets A and B such that every edge in the graph connects a node in set A and a node in set B.
+ * Return true if and only if it is bipartite.
+ */
+
+class Solution {
+public:
+	static bool isBipartite(const std::vector<std::vector<int>>& G) {
+		const int n = G.size();
+		std::vector<uint8_t> colour(n);
+		std::vector<bool> vis(n);
+		std::queue<int> q;
+
+		for (int i = 0; i < n; ++i) {
+			if (vis[i])
+				continue;
+			q.push(i);
+			colour[i] = 1;
+			vis[i] = true;
+			while (!q.empty()) {
+				auto idx = q.front();
+				q.pop();
+				auto nextColour = colour[idx] ^ 3;
+				for (int idxNext : G[idx]) {
+					if (vis[idxNext]) {
+						if (colour[idxNext] != nextColour)
+							return false;
+						continue;
+					}
+					vis[idxNext] = true;
+					colour[idxNext] = nextColour;
+					q.push(idxNext);
+				}
+			}
+		}
+		return true;
+	}
+};

cpp/2204/CMakeLists.txt

@@ -3,4 +3,4 @@ PROJECT(2204)
 
 SET(CMAKE_CXX_STANDARD 23)
 
-ADD_EXECUTABLE(2204 220428.cpp)
+ADD_EXECUTABLE(2204 220429.cpp)