Summary: Added an iterative implementation of the find function in the union-find template to prevent stack overflow problems caused by recursive calls.

.obsidian/app.json

@@ -0,0 +1 @@
+{}

.obsidian/appearance.json

@@ -0,0 +1,3 @@
+{
+  "accentColor": ""
+}

.obsidian/core-plugins-migration.json

@@ -0,0 +1,30 @@
+{
+  "file-explorer": true,
+  "global-search": true,
+  "switcher": true,
+  "graph": true,
+  "backlink": true,
+  "canvas": true,
+  "outgoing-link": true,
+  "tag-pane": true,
+  "properties": false,
+  "page-preview": true,
+  "daily-notes": true,
+  "templates": true,
+  "note-composer": true,
+  "command-palette": true,
+  "slash-command": false,
+  "editor-status": true,
+  "bookmarks": true,
+  "markdown-importer": false,
+  "zk-prefixer": false,
+  "random-note": false,
+  "outline": true,
+  "word-count": true,
+  "slides": false,
+  "audio-recorder": false,
+  "workspaces": false,
+  "file-recovery": true,
+  "publish": false,
+  "sync": false
+}

.obsidian/core-plugins.json

@@ -0,0 +1,20 @@
+[
+  "file-explorer",
+  "global-search",
+  "switcher",
+  "graph",
+  "backlink",
+  "canvas",
+  "outgoing-link",
+  "tag-pane",
+  "page-preview",
+  "daily-notes",
+  "templates",
+  "note-composer",
+  "command-palette",
+  "editor-status",
+  "bookmarks",
+  "outline",
+  "word-count",
+  "file-recovery"
+]

.obsidian/workspace.json

@@ -0,0 +1,147 @@
+{
+  "main": {
+    "id": "14608cf8b641f651",
+    "type": "split",
+    "children": [
+      {
+        "id": "7b559c19d2418ebd",
+        "type": "tabs",
+        "children": [
+          {
+            "id": "a006865600bc4e20",
+            "type": "leaf",
+            "state": {
+              "type": "empty",
+              "state": {}
+            }
+          }
+        ]
+      }
+    ],
+    "direction": "vertical"
+  },
+  "left": {
+    "id": "340e6a79c670a47b",
+    "type": "split",
+    "children": [
+      {
+        "id": "c5f81ca398c18cda",
+        "type": "tabs",
+        "children": [
+          {
+            "id": "51f9f8f44ecceb89",
+            "type": "leaf",
+            "state": {
+              "type": "file-explorer",
+              "state": {
+                "sortOrder": "alphabetical"
+              }
+            }
+          },
+          {
+            "id": "0cff567244d7cff5",
+            "type": "leaf",
+            "state": {
+              "type": "search",
+              "state": {
+                "query": "1971",
+                "matchingCase": false,
+                "explainSearch": false,
+                "collapseAll": false,
+                "extraContext": false,
+                "sortOrder": "alphabetical"
+              }
+            }
+          },
+          {
+            "id": "209574c920774a4d",
+            "type": "leaf",
+            "state": {
+              "type": "bookmarks",
+              "state": {}
+            }
+          }
+        ],
+        "currentTab": 1
+      }
+    ],
+    "direction": "horizontal",
+    "width": 300
+  },
+  "right": {
+    "id": "93ce8f4c11893983",
+    "type": "split",
+    "children": [
+      {
+        "id": "da8cbb56e5ee7c52",
+        "type": "tabs",
+        "children": [
+          {
+            "id": "dfccbc1ebc0bb831",
+            "type": "leaf",
+            "state": {
+              "type": "backlink",
+              "state": {
+                "collapseAll": false,
+                "extraContext": false,
+                "sortOrder": "alphabetical",
+                "showSearch": false,
+                "searchQuery": "",
+                "backlinkCollapsed": false,
+                "unlinkedCollapsed": true
+              }
+            }
+          },
+          {
+            "id": "9d2201419a111fe4",
+            "type": "leaf",
+            "state": {
+              "type": "outgoing-link",
+              "state": {
+                "linksCollapsed": false,
+                "unlinkedCollapsed": true
+              }
+            }
+          },
+          {
+            "id": "dc86ccf1b01bc02c",
+            "type": "leaf",
+            "state": {
+              "type": "tag",
+              "state": {
+                "sortOrder": "frequency",
+                "useHierarchy": true
+              }
+            }
+          },
+          {
+            "id": "ec512545d2a7f2e5",
+            "type": "leaf",
+            "state": {
+              "type": "outline",
+              "state": {}
+            }
+          }
+        ]
+      }
+    ],
+    "direction": "horizontal",
+    "width": 300,
+    "collapsed": true
+  },
+  "left-ribbon": {
+    "hiddenItems": {
+      "switcher:打开快速切换": false,
+      "graph:查看关系图谱": false,
+      "canvas:新建白板": false,
+      "daily-notes:打开/创建今天的日记": false,
+      "templates:插入模板": false,
+      "command-palette:打开命令面板": false
+    }
+  },
+  "active": "a006865600bc4e20",
+  "lastOpenFiles": [
+    "problems/1971.寻找图中是否存在路径.md",
+    "README.md"
+  ]
+}

problems/1971.寻找图中是否存在路径.md

@@ -47,11 +47,22 @@ void init() {
         father[i] = i;
     }
 }
-// 并查集里寻根的过程
+// 并查集里寻根的过程，这里递归调用当题目数据过多，递归调用可能会发生栈溢出
+
 int find(int u) {
     return u == father[u] ? u : father[u] = find(father[u]); // 路径压缩
 }
 
+// 使用迭代的方法可以避免栈溢出问题
+int find(int x) {
+  while (x != parent[x]) {
+	// 路径压缩，直接将x链接到其祖先节点，减少树的高度
+	parent[x] = parent[parent[x]];
+	x = parent[x];
+	}
+return x;
+}
+
 // 判断 u 和 v是否找到同一个根
 bool isSame(int u, int v) {
     u = find(u);
@@ -84,6 +95,8 @@ void join(int u, int v) {
 
 此时我们就可以直接套用并查集模板。
 
+本题在join函数调用find函数时如果是递归调用会发生栈溢出提示，建议使用迭代方法
+
 使用 join(int u, int v)将每条边加入到并查集。
 
 最后 isSame(int u, int v) 判断是否是同一个根 就可以了。
@@ -102,8 +115,13 @@ private:
         }
     }
     // 并查集里寻根的过程
-    int find(int u) {
+    int find(int x) {
-        return u == father[u] ? u : father[u] = find(father[u]);
+      while (x != parent[x]) {
+	      // 路径压缩，直接将x链接到其祖先节点，减少树的高度
+	      parent[x] = parent[parent[x]];
+	      x = parent[x];
+	      }
+      return x;
     }
 
     // 判断 u 和 v是否找到同一个根