javascript - 尽管满足停止条件，递归函数仍不返回

Question

我正在尝试在 Tree 类上编写一个 contains 函数来检查树是否包含值。尽管满足了我的停止条件(通过控制台日志验证)，但该函数未返回 true。

class Tree {
  constructor (value) {
    this.value = value;
    this.children = [];
  }

  addChild (tree) {
    this.children.push(tree);
    return true;
  }

  contains (value) {
    if (this.value === value) {
      return true;
    }
    if (this.children.length === 0) return false;
    for (let tree of this.children) {
      tree.contains(value);
    }
  }
}


const tree = new Tree('hello');
const subTree = new Tree('world');
console.log(tree.addChild(subTree) === true);
console.log(tree.contains('world') === true);

Answer 1

您需要从子级中返回第一个 true 查找结果，最后返回 false 作为默认值。

class Tree {
  constructor (value) {
    this.value = value;
    this.children = [];
  }

  addChild (tree) {
    this.children.push(tree);
    return true;
  }

  contains (value) {
    if (this.value === value) {
      return true;
    }
    if (this.children.length === 0) return false;
    for (let tree of this.children) {
      if (tree.contains(value)) {
          return true;
      }
    }
    return false;
  }
}

const tree = new Tree('hello');
const subTree = new Tree('world');
console.log(tree.addChild(subTree) === true);
console.log(tree.contains('world') === true);