如何解决Javascript递归树搜索?

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试图找出如何递归地搜索这个JSON对象中的节点,我试过一些东西,但没有得到:

var tree = {
    "id": 1,
    "label": "A",
    "child": [
        {
            "id": 2,
            "label": "B",
            "child": [
                {
                    "id": 5,
                    "label": "E",
                    "child": []
                },
                {
                    "id": 6,
                    "label": "F",
                    "child": []
                },
                {
                    "id": 7,
                    "label": "G",
                    "child": []
                }
            ]
        },
        {
            "id": 3,
            "label": "C",
            "child": []
        },
        {
            "id": 4,
            "label": "D",
            "child": [
                {
                    "id": 8,
                    "label": "H",
                    "child": []
                },
                {
                    "id": 9,
                    "label": "I",
                    "child": []
                }
            ]
        }
    ]
};
function scan(id, tree) {
    if(tree.id == id) {
        return tree.label;
    }

    if(tree.child == 0) {
        return
    }

    return scan(tree.child);
};
提问于
用户回答回答于

你的代码只是缺少一个循环来检查child数组中节点的每个子节点,此递归函数将返回label节点的属性或undefined树中不存在标签:

const search = (tree, target) => {
  if (tree.id === target) {
    return tree.label;
  }
  
  for (const child of tree.child) {
    const res = search(child, target);
    
    if (res) {
      return res;
    }
  }
};


var tree = {"id":1,"label":"A","child":[{"id":2,"label":"B","child":[{"id":5,"label":"E","child":[]},{"id":6,"label":"F","child":[]},{"id":7,"label":"G","child":[]}]},{"id":3,"label":"C","child":[]},{"id":4,"label":"D","child":[{"id":8,"label":"H","child":[]},{"id":9,"label":"I","child":[]}]}]};

console.log(search(tree, 1));
console.log(search(tree, 6));
console.log(search(tree, 99));

也可以使用显式堆栈迭代地执行此操作,该堆栈更快,更冷并且不会导致堆栈溢出:

const search = (tree, target) => {
  const stack = [tree];
  
  while (stack.length) {
    const curr = stack.pop();
    
    if (curr.id === target) {
      return curr.label;
    }

    stack.push(...curr.child);
  }
};


var tree = {"id":1,"label":"A","child":[{"id":2,"label":"B","child":[{"id":5,"label":"E","child":[]},{"id":6,"label":"F","child":[]},{"id":7,"label":"G","child":[]}]},{"id":3,"label":"C","child":[]},{"id":4,"label":"D","child":[{"id":8,"label":"H","child":[]},{"id":9,"label":"I","child":[]}]}]};

for (let i = 0; ++i < 12; console.log(search(tree, i)));

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