树的两种遍历方法

先简单看下树的结构

const tree = {
    name: 'A',
    children: [
        {
          name: 'B',
          children: [
            {name: 'D'},
            {name: 'E'},
          ]
        },
        {
          name: 'C',
          children: [
            {name: 'F'},
            {name: 'G'}
          ]
        }
    ]
}

一、深度优先遍历

先遍历根节点，然后在遍历左子树，直到左子树全部遍历完，再去遍历右子树。

let nodes= [];
function dfs(root) {
    nodes.push(root.name);
    if (root.children) {
        root.children.forEach(dfs);
    }
    return nodes;
}
    
const result = dfs(tree);
console.log(result);

二、广度优先遍历

先遍历根节点，然后在遍历第一层的子节点，完事后在遍历第二层子节点，依此类推，逐层遍历

let nodes = [];
    function bfs(root) {
      const quenee = [root];
      while (quenee.length > 0) {
        const node = quenee.shift();
        nodes.push(node.name);
        if (node.children) {
          node.children.forEach(child => {
            quenee.push(child);
          })
        }
    }
    return nodes;
}

const result = bfs(tree);
console.log(result);