147 lines
3.7 KiB
Java
147 lines
3.7 KiB
Java
package com.ktg.common.utils;
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import org.springframework.stereotype.Service;
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import java.util.*;
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/**
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* @author yinjinlu
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* @description 物料BOM环形依赖关系有向图检测
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* @date 2024/12/18
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*/
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@Service
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public class MapCircleUtils {
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private Map<Long,List<Long>> adj; // 邻接表
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private MapCircleUtils() {
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this.adj = new HashMap<>();
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}
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// 静态工厂方法，用于创建实例
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public static MapCircleUtils createInstance() {
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return new MapCircleUtils();
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}
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public void clear() {
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adj.clear();
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}
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/**
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* 向图中添加一条从顶点v到顶点w的边（无向图则双向添加）
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* @param v 起点
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* @param w 终点
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*/
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public void addEdge(Long v, Long w) {
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adj.putIfAbsent(v, new ArrayList<>());
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adj.putIfAbsent(w, new ArrayList<>());
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adj.get(v).add(w);
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// adj.get(w).add(v); // 对于无向图，添加反向边
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}
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/**
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* 向图中添加一个节点（如果节点已存在，则不执行任何操作）
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* @param vertex 要添加的节点
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*/
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public void addVertex(Long vertex) {
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adj.putIfAbsent(vertex, new ArrayList<>());
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}
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/**
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* 返回图中的顶点数量
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* @return
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*/
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public int getVertices() {
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return adj.size();
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}
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/**
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* 检测从顶点 v 出发是否存在环
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* @param v
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* @param visited
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* @param onStack
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* @return
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*/
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private boolean isCircleUtil(Long v, boolean[] visited, boolean[] onStack) {
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if (visited[v.intValue()]) {
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return true; // 已经访问过，说明有环
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}
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if (onStack[v.intValue()]) {
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return false; // 已访问过且不在递归栈中
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}
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visited[v.intValue()] = true;
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onStack[v.intValue()] = true;
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for (Long w : adj.getOrDefault(v, Collections.emptyList())) {
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if (isCircleUtil(w, visited, onStack)) {
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return true;
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}
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}
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onStack[v.intValue()] = false;
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return false;
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}
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/**
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* 图中顶点索引的最大值
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* @return
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*/
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private Long getMaxVertextIndex(){
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return adj.isEmpty() ? -1L : Collections.max(adj.keySet());
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}
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/**
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* 检测图中是否存在环
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* @return
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*/
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public boolean hasCircle() {
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Long max = getMaxVertextIndex();
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boolean[] visited = new boolean[(int) (max + 1)];
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boolean[] onStack = new boolean[(int) (max + 1)];
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for ( Long vertext: adj.keySet()) {
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if (!visited[vertext.intValue()] && isCircleUtil(vertext, visited, onStack)) {
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return true;
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}
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}
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return false;
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}
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public boolean hasCycle() {
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Set<Long> visited = new HashSet<>();
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Set<Long> inPath = new HashSet<>();
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for (Long node : adj.keySet()) {
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if (!visited.contains(node)) {
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if (dfs(adj, node, visited, inPath)) {
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return true;
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}
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}
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}
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return false;
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}
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private boolean dfs(Map<Long, List<Long>> graph, Long node, Set<Long> visited, Set<Long> inPath) {
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visited.add(node);
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inPath.add(node);
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List<Long> neighbors = graph.get(node);
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if (neighbors != null) {
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for (Long neighbor : neighbors) {
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if (!visited.contains(neighbor)) {
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if (dfs(graph, neighbor, visited, inPath)) {
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return true;
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}
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} else if (inPath.contains(neighbor)) {
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return true;
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}
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}
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}
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inPath.remove(node); // 回溯时移除当前节点
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return false;
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}
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}
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