javascript实现多叉树遍历和查找

版权声明：本文为博主原创文章，未经博主允许不得转载。 https://blog.csdn.net/michael51/article/details/88213507

	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;
		}
	}

	//图示
	//http://note.youdao.com/noteshare?id=2e5ea66c27407329937f432fc2457aef&sub=1BE0366303D84814AF4B2E5A0A3E4960
	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)
		 .add('x', 'f', tree.traverseBF)
		 .add('y', 'x', tree.traverseBF);

	console.group('深度优先遍历');
	tree.traverseDF(function (node) {
		console.log(node.data);
	});
	console.groupEnd();

	console.group('广度优先遍历');
	tree.traverseBF(function (node) {
		console.log(node.data);
	});
	console.groupEnd();

	// 深度优先查找
	console.group('深度优先查找f');
	tree.contains(function (node) {
		console.log(node.data);
		if (node.data === 'f') {
			return true;
		}
	}, tree.traverseDF);
	console.groupEnd()

	// 广度优先查找
	console.group('广度优先查找f');
	tree.contains(function (node) {
		console.log(node.data);
		if (node.data === 'f') {
			return true;
		}
	}, tree.traverseBF);
	console.groupEnd();

	//按照深度优先遍历并且移除g和c。
	tree.remove('g', 'c', tree.traverseBF);

	console.group('移除元素之后再次深度优先遍历');
	tree.traverseDF(function (node) {
		console.log(node.data);
	});
	console.groupEnd();