diff --git a/problems/kamacoder/0095.城市间货物运输II.md b/problems/kamacoder/0095.城市间货物运输II.md index 5bc4be7b..6226eb01 100644 --- a/problems/kamacoder/0095.城市间货物运输II.md +++ b/problems/kamacoder/0095.城市间货物运输II.md @@ -244,6 +244,92 @@ int main() { ## 其他语言版本 ### Java +```Java +import java.util.*; + +public class Main { + // 基于SPFA方法 + // Define an inner class Edge + static class Edge { + int from; + int to; + int val; + public Edge(int from, int to, int val) { + this.from = from; + this.to = to; + this.val = val; + } + } + + public static void main(String[] args) { + // Input processing + Scanner sc = new Scanner(System.in); + int n = sc.nextInt(); + int m = sc.nextInt(); + List> graph = new ArrayList<>(); + + for (int i = 0; i <= n; i++) { + graph.add(new ArrayList<>()); + } + + for (int i = 0; i < m; i++) { + int from = sc.nextInt(); + int to = sc.nextInt(); + int val = sc.nextInt(); + graph.get(from).add(new Edge(from, to, val)); + } + + // Declare the minDist array to record the minimum distance form current node to the original node + int[] minDist = new int[n + 1]; + Arrays.fill(minDist, Integer.MAX_VALUE); + minDist[1] = 0; + + // Declare a queue to store the updated nodes instead of traversing all nodes each loop for more efficiency + Queue queue = new LinkedList<>(); + queue.offer(1); + + // Declare an array to record the times each node has been offered in the queue + int[] count = new int[n + 1]; + count[1]++; + + // Declare a boolean array to record if the current node is in the queue to optimise the processing + boolean[] isInQueue = new boolean[n + 1]; + + // Declare a boolean value to check if there is a negative weight loop inside the graph + boolean flag = false; + + while (!queue.isEmpty()) { + int curNode = queue.poll(); + isInQueue[curNode] = false; // Represents the current node is not in the queue after being polled + for (Edge edge : graph.get(curNode)) { + if (minDist[edge.to] > minDist[edge.from] + edge.val) { // Start relaxing the edge + minDist[edge.to] = minDist[edge.from] + edge.val; + if (!isInQueue[edge.to]) { // Don't add the node if it's already in the queue + queue.offer(edge.to); + count[edge.to]++; + isInQueue[edge.to] = true; + } + + if (count[edge.to] == n) { // If some node has been offered in the queue more than n-1 times + flag = true; + while (!queue.isEmpty()) queue.poll(); + break; + } + } + } + } + + if (flag) { + System.out.println("circle"); + } else if (minDist[n] == Integer.MAX_VALUE) { + System.out.println("unconnected"); + } else { + System.out.println(minDist[n]); + } + } +} + +``` ### Python