JavaScript递归树搜索函数未检测到嵌套子代

Question

试图制作一个递归函数，该函数能够正确搜索树类及其所有后代的值，并在找到该值时返回true，否则返回false。

特别重要的是递归contains（）函数。试图让代码通过linter。我只有一个关于未检测到嵌套的孩子的错误。其他一切都在流逝。

我的代码：

/* eslint-disable no-trailing-spaces */ 
/* eslint-disable no-unused-vars */ 
class Tree { 
    constructor(value) { 
    this.value = value; 
    this.children = []; 
    } 
    // Adds a new Tree node with the input value to the current Tree node 
    addChild(value) { 
    this.children.push(new Tree(value)); 
    } 
    // Checks this node's children to see if any of them matches the given value 
    // Continues recursively until the value has been found or all of the children 
    // have been checked 
    contains(value) { 
    const thisNode = this; 
    function checkNode(node) { 
     if (node.value === value) { 
     return true; 
     } 
     if (node.children.length > 0) { 
     for (let i = 0; i < node.children.length; i++) { 
      return checkNode(node.children[i]); 
     } 
     } 
     return false; 
    } 
    return checkNode(thisNode); 
    } 
} 

module.exports = Tree; 

下面是测试中，它的文件：

/* eslint-disable no-undef */ 
const Tree = require('../src/tree'); 

describe('Tree',() => { 
    let tree; 

    beforeEach(() => { 
    tree = new Tree(true); 
    }); 

    it('should have methods named "addChild" and "contains"',() => { 
    expect(typeof tree.addChild).toBe('function'); 
    expect(typeof tree.contains).toBe('function'); 
    }); 

    it('should add children to the tree',() => { 
    tree.addChild(5); 
    expect(tree.children[0].value).toBe(5); 
    }); 

    it('should return true for a value that the tree contains',() => { 
    tree.addChild(5); 
    expect(tree.contains(5)).toBe(true); 
    }); 

    it('should return false for a value that was not added',() => { 
    tree.addChild(5); 
    expect(tree.contains(6)).toBe(false); 
    }); 

    it('should be able to add children to a tree\'s child',() => { 
    tree.addChild(5); 
    tree.children[0].addChild(6); 
    expect(tree.children[0].children[0].value).toBe(6); 
    }); 

    it('should correctly detect nested children',() => { 
    tree.addChild(5); 
    tree.addChild(6); 
    tree.children[0].addChild(7); 
    tree.children[1].addChild(8); 
    expect(tree.contains(7)).toBe(true); 
    expect(tree.contains(8)).toBe(true); 
    }); 
}); 

这里是掉毛的错误：

Tree 
    ✓ should have methods named "addChild" and "contains" (5ms) 
    ✓ should add children to the tree (1ms) 
    ✓ should return true for a value that the tree contains (3ms) 
    ✓ should return false for a value that was not added (1ms) 
    ✓ should be able to add children to a tree's child (1ms) 
    ✕ should correctly detect nested children (9ms) 

Answer 1

您无条件换内返回循环，所以你只能检查第一个孩子。

for (let i = 0; i < node.children.length; i++) { 
     return checkNode(node.children[i]); 
    } 

应该

for (let i = 0; i < node.children.length; i++) { 
     if (checkNode(node.children[i])) return true; 
    } 

Answer 2

我想，这是你的代码应该是什么样子：

for (let childIndex = 0; childIndex < node.children.length; childIndex++) { 
    const foundInChildren = checkNode(node.children[childIndex]); 
    if (foundInChildren) 
    return true; 
} 

Answer 3

您的问题是在这大块的代码在这里：

if (node.children.length > 0) { 
    for (let i = 0; i < node.children.length; i++) { 
     return checkNode(node.children[i]); 
    } 
    } 

这行代码将从该函数无论checkNode的结果是第一个孩子，true还是false。如果结果为false，则需要继续检查。

试试这个：

if (node.children.length > 0) { 
    for (let i = 0; i < node.children.length; i++) { 
     if (checkNode(node.children[i])) { 
     return true; 
     } 
    } 
    }