前端筆試中兩道與節點有關的算法題

1.分別用廣度優先遍歷和深度優先遍歷展開下面節點

• 示例

var tree = {
    name: 'root',
    children: [{
        name: 'child1',
        children: [{
            name: 'child1_1',
            children: []
        }, { name: 'child1_2', children: [] }]
    }, {
        name: 'child2',
        children: [{
            name: 'child2_1',
            children: []
        }]
    }, {
        name: 'child3',
        children: [{
            name: 'child2_1',
            children: []
        }]
    }]
};
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廣度優先遍歷：

function wideTraversal(node) {
    var nodes = [];
    if (node != null) {
        var queue = [];
        queue.unshift(node);
        while (queue.length != 0) {
            var item = queue.shift();
            nodes.push(item.name);
            var children = item.children;
            for (var i = 0; i < children.length; i++) {

                queue.push(children[i]);
            }
        }

    }
    return nodes;
}
console.log(wideTraversal(tree))
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輸出結果：

[ 'root','child1','child2','child3','child1_1','child1_2','child2_1','child2_1' ]

深度優先遍歷：

function traverseTree(node) {
    var child = node.children,
        arr = [];

    arr.push(node.name);
    if (child) {
        child.forEach(function(node) {
            arr = arr.concat(traverseTree(node));
        });
    }
    return arr;
}
console.log(traverseTree(tree))
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輸出結果：

[ 'root','child1','child1_1','child1_2','child2','child2_1','child3','child2_1' ]

2.關係型數組轉換成樹形結構對象

相似：

var data = [
    { parentId: 0, id: 1, value: '1' },
    { parentId: 3, id: 2, value: '2' },
    { parentId: 0, id: 3, value: '3' },
    { parentId: 1, id: 4, value: '4' },
    { parentId: 1, id: 5, value: '5' }
]
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指望輸出：

[
{id:1,value:'1',
children:[{id:4,value:'4',children:[]},
{id:5,value:'5',children:[]}]},
{id:3,value:'3',
children:[id:2,value:'2',children:[]]}]
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代碼：

var getJsonTree = function(data, parentId) {
    var itemArr = [];
    for (var i = 0; i < data.length; i++) {
        var node = data[i];
        //data.splice(i, 1)
        if (node.parentId == parentId) {
            var newNode = { id: node.id, value: node.value, children: getJsonTree(data, node.id) };
            itemArr.push(newNode);
        }
    }
    return itemArr;
}
console.log(getJsonTree(data, 0))
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