add: 220514 [cpp]

cpp/2205/220514.cpp

@@ -0,0 +1,59 @@
+#include <vector>
+#include <tuple>
+#include <queue>
+#include <iostream>
+
+/**
+ * 743. Network Delay Time
+ * You are given a network of n nodes, labeled from 1 to n. You are also given times, a list of travel times as directed edges times[i] = (ui, vi, wi), where ui is the source node, vi is the target node, and wi is the time it takes for a signal to travel from source to target.
+ * We will send a signal from a given node k. Return the time it takes for all the n nodes to receive the signal. If it is impossible for all the n nodes to receive the signal, return -1.
+ *
+ * Comment: This is Dijkstra's algorithm.
+ */
+
+class Solution {
+public:
+	static int networkDelayTime(const std::vector<std::vector<int>>& times, int n, int k) {
+		const int edgeCnt = times.size();
+		std::vector<std::tuple<int, int, int>> edges;
+		std::vector<std::vector<int>> G(n);
+		edges.reserve(edgeCnt);
+		for (int i = 0; i < edgeCnt; ++i) {
+			edges.emplace_back(times[i][0] - 1, times[i][1] - 1, times[i][2]);
+			G[times[i][0] - 1].push_back(i);
+		}
+
+		std::vector<int> dist(n, 0x6FFFFFFF);
+		std::vector<bool> vis(n);
+		--k;
+
+		// pair<dist, idx>
+		std::priority_queue<std::pair<int, int>, std::vector<std::pair<int, int>>, std::greater<>> q;
+		q.push({0, k});
+		dist[k] = 0;
+		while (!q.empty()) {
+			const auto [len, node] = q.top();
+			q.pop();
+
+			if (vis[node])
+				continue;
+			vis[node] = true;
+
+			for (int eId : G[node]) {
+				const auto [f, t, d] = edges[eId];
+				if (dist[t] <= dist[node] + d)
+					continue;
+				dist[t] = dist[node] + d;
+				q.push({dist[t], t});
+			}
+		}
+
+		int ret = *std::max_element(dist.begin(), dist.end());
+		return ret == 0x6FFFFFFF ? -1 : ret;
+	}
+};
+
+int main() {
+	std::cout << Solution::networkDelayTime({{2,1,1},{2,3,1},{3,4,1}}, 4, 2);
+	return 0;
+}

cpp/2205/CMakeLists.txt

@@ -3,4 +3,4 @@ PROJECT(2205)
 
 SET(CMAKE_CXX_STANDARD 23)
 
-ADD_EXECUTABLE(2205 220514-CN.cpp)
+ADD_EXECUTABLE(2205 220514.cpp)