Trie

Author: tianqing.liang

16-Segment-Tree/Main.dart

@@ -11,8 +11,10 @@ class NewMerger<E> implements Merger{
 
 void main(){
   List nums = [-2, 0, 3, -5, 2, -1];
-  Merger<num> selfMerger = NewMerger() as Merger<num>;
-  SegmentTree<num> segTree = SegmentTree(nums, selfMerger);
+//  NewMerger<num> selfMerger = NewMerger<num>();
+//  SegmentTree segTree = SegmentTree(nums, selfMerger);
+  SegmentTree segmentTreeSec = SegmentTree(nums, new NewMerger());
+  print(segmentTreeSec.toString());
 }
 
 

16-Segment-Tree/Merger.dart

@@ -1,6 +1,4 @@
 abstract class Merger<E>{
-
     E merge(E a, E b);
-
 }
 

16-Segment-Tree/Segment.dart

@@ -60,18 +60,76 @@ class SegmentTree<E> {
     return 2 * index + 2;
   }
 
+  query(int queryL, int queryR) {
+    if (queryL < 0 ||
+        queryL >= _data!.length ||
+        queryR < 0 ||
+        queryR >= _data!.length ||
+        queryL > queryR) {
+      throw new Exception("Index is illegal.");
+    }
+    return _queryDetail(0, 0, _data!.length - 1, queryL, queryR);
+  }
+
+  _queryDetail(int treeIndex, int l, int r, int queryL, int queryR) {
+    if (l == queryL && r == queryR) {
+      return _tree![treeIndex];
+    }
+    int mid = l + ((r - l) / 2).toInt();
+    // treeIndex的节点分为[l...mid]和[mid+1...r]两部分
+
+    int leftTreeIndex = _leftChild(treeIndex);
+    int rightTreeIndex = _rightChild(treeIndex);
+    if (queryL >= mid + 1) {
+      return _queryDetail(rightTreeIndex, mid + 1, r, queryL, queryR);
+    } else if (queryR <= mid) {
+      return _queryDetail(leftTreeIndex, l, mid, queryL, queryR);
+    }
+    E leftResult = _queryDetail(leftTreeIndex, l, mid, queryL, mid);
+    E rightResult = _queryDetail(rightTreeIndex, mid + 1, r, mid + 1, queryR);
+    return _merger!.merge(leftResult, rightResult);
+  }
+
+  //将index位置的值，更新为e
+  set(int index, E e){
+    if(index < 0 || index >= _data!.length) {
+      throw new Exception("Index is illegal");
+    }
+    _data![index] = e;
+    _setDetail(0, 0, _data!.length - 1, index, e);
+  }
+
+  // 在以treeIndex为根的线段树中更新index的值为e
+  _setDetail(int treeIndex, int l, int r, int index, E e){
+    if(l == r){
+      _tree![treeIndex] = e;
+      return;
+    }
+    int mid = l + ((r - l) / 2).toInt();
+    // treeIndex的节点分为[l...mid]和[mid+1...r]两部分
+    int leftTreeIndex = _leftChild(treeIndex);
+    int rightTreeIndex = _rightChild(treeIndex);
+    if(index >= mid + 1) {
+      _setDetail(rightTreeIndex, mid + 1, r, index, e);
+    }else { // index <= mid
+      _setDetail(leftTreeIndex, l, mid, index, e);
+    }
+    _tree![treeIndex] = _merger!.merge(_tree![leftTreeIndex], _tree![rightTreeIndex]);
+  }
+
   @override
   String toString() {
     StringBuffer res = new StringBuffer();
     res.write('[');
-    for(int i = 0 ; i < _tree!.length ; i ++){
-      if(_tree![i] != null)
+    for (int i = 0; i < _tree!.length; i++) {
+      if (_tree![i] != null) {
         res.write(_tree![i]);
-      else
+      } else {
         res.write("null");
-
-      if(i != _tree!.length - 1)
+      }
+      if (i != _tree!.length - 1) {
         res.write(", ");
+      }
     }
     res.write(']');
     return res.toString();

17-Trie/FileOperator.dart

@@ -0,0 +1,19 @@
+import 'dart:io';
+import 'dart:convert';
+
+/**
+ * 文件操作类
+ */
+class FileOperator{
+
+    static Future<List> getFileString(String filename) async{
+      Stream<List<int>> content = File(filename).openRead();
+      List<String> lines = await content.transform(utf8.decoder).transform(LineSplitter()).toList();
+      var words = [];
+      for(int i = 0;i<lines.length;i++){
+        words.addAll(lines[i].split(" ").toList());
+      }
+      words.removeWhere((element) => element == "");
+      return words;
+    }
+}

17-Trie/Main.dart

@@ -0,0 +1,29 @@
+import 'dart:io';
+import 'dart:convert';
+
+import 'Trie.dart';
+import 'FileOperator.dart';
+void main() async{
+
+  List result = await FileOperator.getFileString('text2.txt');
+//  print(result);
+  print("总数量：${result.length}");
+  var now = new DateTime.now();
+  num startTime = now.millisecondsSinceEpoch;
+
+  Trie trie = new Trie();
+  for(String word in result)
+    trie.add(word);
+
+  for(String word in result)
+    trie.contains(word);
+
+  var endNow = new DateTime.now();
+  num endTime = endNow.millisecondsSinceEpoch;
+  print("开始时间：$startTime : 结束时间:$endTime");
+  double time = (endTime - startTime) / 1000.0;
+
+  print("Total different words: ${trie.getSize()}");
+  print("Trie: $time   s");
+
+}

17-Trie/Trie.dart

@@ -0,0 +1,72 @@
+import 'dart:collection';
+
+class Trie {
+  _Node? _root;
+
+  int? _size;
+
+  Trie() {
+    _root = _Node();
+    _size = 0;
+  }
+
+  int? getSize() {
+    return _size;
+  }
+
+  add(String? word) {
+    _Node? cur = _root;
+    for (int i = 0; i < word!.length; i++) {
+      String c = word[i];
+      if (cur!.next![c] == null) {
+        cur.next!.putIfAbsent(c, () => _Node());
+      }
+      cur = cur.next![c];
+    }
+    if (!(cur!.isWord!)) {
+      cur.isWord = true;
+      _size = _size! + 1;
+    }
+  }
+
+  // 查询单词word是否在Trie中
+  bool contains(String word) {
+    _Node? cur = _root;
+    for (int i = 0; i < word.length; i++) {
+      String c = word[i];
+      if (cur!.next![c] == null) {
+        return false;
+      }
+      cur = cur.next![c];
+    }
+    return cur!.isWord!;
+  }
+
+  // 查询是否在Trie中有单词以prefix为前缀
+  bool isPrefix(String prefix){
+    _Node? cur = _root;
+    for(int i = 0 ; i < prefix!.length ; i ++){
+      String c = prefix[i];
+      if(cur!.next![c] == null){
+        return false;
+      }
+      cur = cur.next![c];
+    }
+    return true;
+  }
+}
+
+class _Node {
+  bool? isWord;
+
+  SplayTreeMap<String, _Node>? next;
+
+  _Node.isWord(bool isWord) {
+    this.isWord = isWord;
+    next = new SplayTreeMap();
+  }
+
+  factory _Node() {
+    return _Node.isWord(false);
+  }
+}