v10

test/structure/link_list/find.dart

@@ -0,0 +1,204 @@
+/// Dart、Rust 、C++ 、Java
+
+void main() {
+  ListNode listNode = ListNode(0, ListNode(3, ListNode(2, ListNode(8))));
+  print(listNode);
+
+  // List<int> evens = listNode.getEvenValue();
+  // print(evens);
+
+  // List<int> values = listNode.getValueByStep(2);
+  // print(values);
+
+  // listNode.deleteAt(3);
+  // ListNode? ret = listNode.deleteFromEnd(2);
+  // print(ret);
+
+  // ListNode? middleNode1 = listNode.middleNode1();
+  // print(middleNode1);
+
+  ListNode? middleNode2 = listNode.middleNode2();
+  print(middleNode2);
+  // ListNode? findNode = listNode.find(8);
+  // if(findNode!=null){
+  //   ListNode? result =  listNode.deleteNode(findNode);
+  //   // 0->2->8
+  //   print(result);
+  // }
+}
+
+class ListNode {
+  int val;
+  ListNode? next;
+  ListNode([this.val = 0, this.next]);
+
+  //// region [2023.11.20]
+  @override
+  String toString() {
+    ListNode? cur = this;
+    String result = "";
+    while (cur != null) {
+      result = result + cur.val.toString();
+      cur = cur.next;
+      if (cur != null) {
+        result += '->';
+      }
+    }
+    return result;
+  }
+
+  // endregion
+
+  //// region [2023.11.21]
+  /// [2023.11.21] TODO: 完成 find 函数，在链表中查找指定值的首位节点
+  ListNode? find(int target) {
+    ListNode? cur = this;
+    while (cur != null) {
+      if (cur.val == target) {
+        return cur;
+      }
+      cur = cur.next;
+    }
+    return null;
+  }
+
+  /// [2023.11.21]
+  /// TODO: LeetCode 237 删除指定节点(非尾结点)
+  void deleteNodeNotLast(ListNode node) {
+    if (node.next != null) {
+      node.val = node.next!.val;
+      node.next = node.next?.next;
+    }
+  }
+
+  // endregion
+
+  //// region [2023.11.22]
+  /// [2023.11.22]
+  /// TODO: 完成 size 方法，返回链表长度
+  int size() {
+    int i = 0;
+    ListNode? cur = this;
+    while (cur != null) {
+      cur = cur.next;
+      i++;
+    }
+    return i;
+  }
+
+  /// [2023.11.22]
+  /// TODO: 完成 deleteAt 方法，删除第 index 个节点
+  void deleteAt(int index) {
+    if (index == 0) {
+      ListNode? next = this.next;
+      this.val = next?.val ?? -1;
+      this.next = next?.next;
+      next?.next = null;
+      return;
+    }
+
+    ListNode? cur = this;
+    for (int i = 0; i < index - 1; i++) {
+      cur = cur?.next;
+    }
+    ListNode? target = cur?.next;
+    cur?.next = target?.next;
+    target?.next = null;
+  }
+
+  /// [2023.11.22]
+  /// TODO: LeetCode 19 删除链表的倒数第 N 个节点
+  ListNode? deleteFromEnd(int n) {
+    ListNode? dummy = ListNode(0, this);
+    ListNode? first = this;
+    ListNode? second = dummy;
+    for (int i = 0; i < n; ++i) {
+      first = first?.next;
+    }
+    while (first != null) {
+      first = first.next;
+      second = second?.next;
+    }
+    second?.next = second.next?.next;
+    return dummy.next;
+  }
+
+  ListNode? deleteNode(ListNode node) {
+    ListNode? cur = this;
+    if (cur == node) {
+      cur = cur.next!;
+      return cur;
+    }
+    while (cur != null) {
+      if (cur.next == node) {
+        cur.next = cur.next?.next;
+        return this;
+      }
+      cur = cur.next;
+    }
+    return this;
+  }
+
+  // endregion
+
+  //// region [2023.11.23]
+  /// [2023.11.23]
+  /// TODO: 完成 getEvenValue 方法，
+  /// 返回链表中偶数节点的值列表
+  List<int> getEvenValue() {
+    ListNode? cur = this;
+    List<int> result = [];
+
+    while (cur != null) {
+      result.add(cur.val);
+      cur = cur.next?.next;
+    }
+    return result;
+  }
+
+  /// TODO: 完成 getValueByStep 方法，
+  /// 返回链表中每隔 step 个节点的值列表
+  /// 例:
+  /// 链表: 0->3->2->8->9
+  /// step=3 : 输出 [0, 8]
+  /// step=2 : 输出 [0, 2, 9]
+  List<int> getValueByStep(int step) {
+    ListNode? cur = this;
+    List<int> result = [];
+
+    while (cur != null) {
+      result.add(cur.val);
+      for (int i = 0; i < step; i++) {
+        cur = cur?.next;
+      }
+    }
+    return result;
+  }
+
+  /// [2023.11.23]
+  /// TODO: LeetCode 876 链表的中间结点
+  /// [1,2,3,4,5] -> [3,4,5]
+  /// [1,2,3,4,5,6] -> [4,5,6]
+  /// 时间 O(N) 空间 O(N)
+  ListNode? middleNode1() {
+    List<ListNode?> nodes = [];
+    ListNode? cur = this;
+    while (cur != null) {
+      nodes.add(cur);
+      cur = cur.next;
+    }
+    return nodes[nodes.length ~/ 2];
+  }
+
+  /// 使用快慢指针 - 一次遍历
+  ListNode? middleNode2() {
+    ListNode? slow = this;
+    ListNode? fast = this;
+    while (fast != null && fast.next != null) {
+      slow = slow?.next;
+      fast = fast.next?.next;
+    }
+    return slow;
+  }
+// endregion
+}

test/structure/link_list/linked_list.dart

@@ -0,0 +1,3 @@
+class LikedList<T>{
+
+}

test/structure/link_list/print.dart

@@ -23,7 +23,4 @@ class ListNode {
     }
     return result;
   }
-
-
-
 }