javascript数据结构之多叉树怎么实现

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1、创造一个节点

数据是以节点的形式存储的：

class Node {  constructor(data) {    this.data = data;    this.parent = null;    this.children = [];  }}

2、创造树

树用来连接节点，就像真实世界树的主干一样，延伸着很多分支

class MultiwayTree {  constructor() {    this._root = null;  }}

3、添加一个节点

function add(data, toData, traversal) {  let node = new Node(data)  // 第一次添加到根节点  // 返回值为this，便于链式添加节点  if (this._root === null) {    this._root = node;    return this;  }  let parent = null,    callback = function(node) {      if (node.data === toData) {        parent = node;        return true;      }    };  // 根据遍历方法查找父节点（遍历方法后面会讲到），然后把节点添加到父节点  // 的children数组里  // 查找方法contains后面会讲到  this.contains(callback, traversal);  if (parent) {    parent.children.push(node);    node.parent = parent;    return this;  } else {    throw new Error('Cannot add node to a non-existent parent.');  }}

4、深度优先遍历

深度优先会尽量先从子节点查找，子节点查找完再从兄弟节点查找，适合数据深度比较大的情况，如文件目录

function traverseDF(callback) {  let stack = [], found = false;  stack.unshift(this._root);  let currentNode = stack.shift();  while(!found && currentNode) {    // 根据回调函数返回值决定是否在找到第一个后继续查找    found = callback(currentNode) === true ? true : false;    if (!found) {      // 每次把子节点置于堆栈最前头，下次查找就会先查找子节点      stack.unshift(...currentNode.children);      currentNode = stack.shift();    }  }}

5、广度优先遍历

广度优先遍历会优先查找兄弟节点，一层层往下找，适合子项较多情况，如公司岗位级别

function traverseBF(callback) {  let queue = [], found = false;  queue.push(this._root);  let currentNode = queue.shift();  while(!found && currentNode) {    // 根据回调函数返回值决定是否在找到第一个后继续查找    found = callback(currentNode) === true ? true : false;    if (!found) {      // 每次把子节点置于队列最后，下次查找就会先查找兄弟节点      queue.push(...currentNode.children)      currentNode = queue.shift();    }  }}

6、包含节点

function contains(callback, traversal) {  traversal.call(this, callback);}

回调函数算法可自己根据情况实现，灵活度较高

7、移除节点

// 返回被移除的节点function remove(data, fromData, traversal) {  let parent = null,    childToRemove = null,    callback = function(node) {      if (node.data === fromData) {        parent = node;        return true;      }    };  this.contains(callback, traversal);  if (parent) {    let index = this._findIndex(parent.children, data);    if (index < 0) {      throw new Error('Node to remove does not exist.');    } else {      childToRemove = parent.children.splice(index, 1);    }  } else {    throw new Error('Parent does not exist.');  }  return childToRemove;}

_findIndex实现:

function _findIndex(arr, data) {  let index = -1;  for (let i = 0, len = arr.length; i < len; i++) {    if (arr[i].data === data) {      index = i;      break;    }  }  return index;}

完整算法

class Node {  constructor(data) {    this.data = data;    this.parent = null;    this.children = [];  }}class MultiwayTree {  constructor() {    this._root = null;  }  //深度优先遍历  traverseDF(callback) {    let stack = [], found = false;    stack.unshift(this._root);    let currentNode = stack.shift();    while(!found && currentNode) {      found = callback(currentNode) === true ? true : false;      if (!found) {        stack.unshift(...currentNode.children);        currentNode = stack.shift();      }    }  }  //广度优先遍历  traverseBF(callback) {    let queue = [], found = false;    queue.push(this._root);    let currentNode = queue.shift();    while(!found && currentNode) {      found = callback(currentNode) === true ? true : false;      if (!found) {        queue.push(...currentNode.children)        currentNode = queue.shift();      }    }  }  contains(callback, traversal) {    traversal.call(this, callback);  }  add(data, toData, traversal) {    let node = new Node(data)    if (this._root === null) {      this._root = node;      return this;    }    let parent = null,      callback = function(node) {        if (node.data === toData) {          parent = node;          return true;        }      };    this.contains(callback, traversal);    if (parent) {      parent.children.push(node);      node.parent = parent;      return this;    } else {      throw new Error('Cannot add node to a non-existent parent.');    }  }  remove(data, fromData, traversal) {    let parent = null,      childToRemove = null,      callback = function(node) {        if (node.data === fromData) {          parent = node;          return true;        }      };    this.contains(callback, traversal);    if (parent) {      let index = this._findIndex(parent.children, data);      if (index < 0) {        throw new Error('Node to remove does not exist.');      } else {        childToRemove = parent.children.splice(index, 1);      }    } else {      throw new Error('Parent does not exist.');    }    return childToRemove;  }  _findIndex(arr, data) {    let index = -1;    for (let i = 0, len = arr.length; i < len; i++) {      if (arr[i].data === data) {        index = i;        break;      }    }    return index;  }}

控制台测试代码

var tree = new MultiwayTree();tree.add('a')  .add('b', 'a', tree.traverseBF)  .add('c', 'a', tree.traverseBF)  .add('d', 'a', tree.traverseBF)  .add('e', 'b', tree.traverseBF)  .add('f', 'b', tree.traverseBF)  .add('g', 'c', tree.traverseBF)  .add('h', 'c', tree.traverseBF)  .add('i', 'd', tree.traverseBF);console.group('traverseDF');tree.traverseDF(function(node) {  console.log(node.data);});console.groupEnd('traverseDF');console.group('traverseBF');tree.traverseBF(function(node) {  console.log(node.data);});console.groupEnd('traverseBF');// 深度优先查找console.group('contains1');tree.contains(function(node) {  console.log(node.data);  if (node.data === 'f') {    return true;  }}, tree.traverseDF);console.groupEnd('contains1')// 广度优先查找console.group('contains2');tree.contains(function(node) {  console.log(node.data);  if (node.data === 'f') {    return true;  }}, tree.traverseBF);console.groupEnd('contains2');tree.remove('g', 'c', tree.traverseBF);

运行效果如下：

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