From 12e74e35209d9016cf52fed525e94a9240bc1bce Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?yinjinlu-pc=5C=E5=B0=B9=E9=87=91=E8=B7=AF?=
 <411641505@qq.com>
Date: Wed, 15 Jan 2025 09:48:34 +0800
Subject: [PATCH] =?UTF-8?q?=E7=89=A9=E6=96=99=E9=9C=80=E6=B1=82=E6=9C=89?=
 =?UTF-8?q?=E5=90=91=E5=9B=BE=E7=8E=AF=E6=A3=80=E6=B5=8B?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .../com/ktg/common/utils/MapCircleUtils.java  | 72 +++++++++++++++++++
 1 file changed, 72 insertions(+)
 create mode 100644 ktg-common/src/main/java/com/ktg/common/utils/MapCircleUtils.java

diff --git a/ktg-common/src/main/java/com/ktg/common/utils/MapCircleUtils.java b/ktg-common/src/main/java/com/ktg/common/utils/MapCircleUtils.java
new file mode 100644
index 0000000..b0ac05f
--- /dev/null
+++ b/ktg-common/src/main/java/com/ktg/common/utils/MapCircleUtils.java
@@ -0,0 +1,72 @@
+package com.ktg.common.utils;
+
+import org.springframework.stereotype.Service;
+
+import java.util.*;
+
+/**
+ * @author yinjinlu
+ * @description 物料BOM环形依赖关系有向图检测
+ * @date 2024/12/18
+ */
+@Service
+public class MapCircleUtils {
+
+    private Map<Integer,List<Integer>> adj; // 邻接表
+
+    private MapCircleUtils() {
+        this.adj = new HashMap<>();
+    }
+
+
+    public void clear() {
+        adj.clear();
+    }
+
+    public void addEdge(int v, int w) {
+        adj.computeIfAbsent(v, k -> new ArrayList<>()).add(w);
+        adj.computeIfAbsent(w, k -> new ArrayList<>());
+    }
+
+
+    public int getVertices() {
+        return adj.size();
+    }
+
+    private boolean isCircleUtil(Integer v, boolean[] visited, boolean[] onStack) {
+        if (visited[v]) {
+            return true; // 已经访问过，说明有环
+        }
+
+        if (onStack[v]) {
+            return false; // 已访问过且不在递归栈中
+        }
+
+        visited[v] = true;
+        onStack[v] = true;
+
+        for (Integer w : adj.getOrDefault(v, Collections.emptyList())) {
+            if (isCircleUtil(w, visited, onStack)) {
+                return true;
+            }
+        }
+
+        onStack[v] = false;
+        return false;
+    }
+
+    private int getMaxVertextIndex(){
+        return adj.isEmpty() ? -1 : Collections.max(adj.keySet());
+    }
+
+    public boolean hasCircle() {
+        boolean[] visited = new boolean[getMaxVertextIndex() + 1];
+        boolean[] onStack = new boolean[getMaxVertextIndex() + 1];
+        for ( int vertext: adj.keySet()) {
+            if (!visited[vertext] && isCircleUtil(vertext, visited, onStack)) {
+                return true;
+            }
+        }
+        return false;
+    }
+}