2018-10-10 22:03:03 +00:00
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---
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id: 587d825d367417b2b2512c96
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2020-12-16 07:37:30 +00:00
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title: 深度优先搜索
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2018-10-10 22:03:03 +00:00
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challengeType: 1
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videoUrl: ''
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---
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2020-12-16 07:37:30 +00:00
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# --description--
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与<dfn>广度优先搜索</dfn>类似,这里我们将学习另一种称为<dfn>深度优先搜索的</dfn>图遍历算法。广度优先搜索搜索远离源节点的增量边长度,而<dfn>深度优先搜索</dfn>首先尽可能地沿着边缘路径向下<dfn>搜索</dfn> 。一旦到达路径的一端,搜索将回溯到具有未访问边缘路径的最后一个节点并继续搜索。在视觉上,这就是算法正在做的事情,其中顶部节点是搜索的起始点。
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<img class='img-responsive' src='https://camo.githubusercontent.com/aaad9e39961daf34d967c616edeb50abf3bf1235/68747470733a2f2f75706c6f61642e77696b696d656469612e6f72672f77696b6970656469612f636f6d6d6f6e732f372f37662f44657074682d46697273742d5365617263682e676966'>
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该算法的简单输出是可从给定节点到达的节点列表。因此,在实施此算法时,您需要跟踪您访问的节点。
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# --instructions--
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2018-10-10 22:03:03 +00:00
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2020-12-16 07:37:30 +00:00
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编写一个函数`dfs()` ,它将无向,邻接矩阵`graph`和节点标签`root`作为参数。节点标签将只是`0`和`n - 1`之间节点的数值,其中`n`是图中节点的总数。您的函数应输出从`root`可到达的所有节点的数组。
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# --hints--
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输入图`[[0, 1, 0, 0], [1, 0, 1, 0], [0, 1, 0, 1], [0, 0, 1, 0]]` ,起始节点为`1`应返回一个数组`0` , `1` , `2` ,和`3` 。
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```js
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assert.sameMembers(
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(function () {
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var graph = [
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[0, 1, 0, 0],
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[1, 0, 1, 0],
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[0, 1, 0, 1],
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[0, 0, 1, 0]
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];
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return dfs(graph, 1);
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})(),
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[0, 1, 2, 3]
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);
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2018-10-10 22:03:03 +00:00
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```
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2020-12-16 07:37:30 +00:00
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输入图`[[0, 1, 0, 0], [1, 0, 1, 0], [0, 1, 0, 1], [0, 0, 1, 0]]` ,起始节点为`1`应该返回一个包含四个元素的数组。
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2018-10-10 22:03:03 +00:00
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2020-12-16 07:37:30 +00:00
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```js
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assert(
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(function () {
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var graph = [
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[0, 1, 0, 0],
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[1, 0, 1, 0],
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[0, 1, 0, 1],
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[0, 0, 1, 0]
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];
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return dfs(graph, 1);
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})().length === 4
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);
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```
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2018-10-10 22:03:03 +00:00
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2020-12-16 07:37:30 +00:00
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输入图`[[0, 1, 0, 0], [1, 0, 1, 0], [0, 1, 0, 0], [0, 0, 0, 0]]` ,起始节点为`3`应该返回一个`3`的数组。
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2018-10-10 22:03:03 +00:00
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```js
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2020-12-16 07:37:30 +00:00
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assert.sameMembers(
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(function () {
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var graph = [
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[0, 1, 0, 0],
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[1, 0, 1, 0],
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[0, 1, 0, 0],
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[0, 0, 0, 0]
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];
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return dfs(graph, 3);
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})(),
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[3]
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);
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```
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输入图`[[0, 1, 0, 0], [1, 0, 1, 0], [0, 1, 0, 0], [0, 0, 0, 0]]` ,起始节点为`3`应该返回一个包含一个元素的数组。
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2018-10-10 22:03:03 +00:00
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2020-12-16 07:37:30 +00:00
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```js
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assert(
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(function () {
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var graph = [
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[0, 1, 0, 0],
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[1, 0, 1, 0],
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[0, 1, 0, 0],
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[0, 0, 0, 0]
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];
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return dfs(graph, 3);
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})().length === 1
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);
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```
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2018-10-10 22:03:03 +00:00
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2020-12-16 07:37:30 +00:00
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输入图`[[0, 1, 0, 0], [1, 0, 0, 0], [0, 0, 0, 1], [0, 0, 1, 0]]` ,起始节点为`3`应该返回一个`2`和`3`的数组。
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2018-10-10 22:03:03 +00:00
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2020-12-16 07:37:30 +00:00
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```js
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assert.sameMembers(
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(function () {
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var graph = [
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[0, 1, 0, 0],
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[1, 0, 0, 0],
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[0, 0, 0, 1],
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[0, 0, 1, 0]
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];
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return dfs(graph, 3);
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})(),
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[2, 3]
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);
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2018-10-10 22:03:03 +00:00
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```
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2020-12-16 07:37:30 +00:00
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输入图`[[0, 1, 0, 0], [1, 0, 0, 0], [0, 0, 0, 1], [0, 0, 1, 0]]` ,起始节点为`3`应该返回一个包含两个元素的数组。
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2018-10-10 22:03:03 +00:00
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2020-12-16 07:37:30 +00:00
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```js
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assert(
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(function () {
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var graph = [
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[0, 1, 0, 0],
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[1, 0, 0, 0],
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[0, 0, 0, 1],
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[0, 0, 1, 0]
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];
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return dfs(graph, 3);
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})().length === 2
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);
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```
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2018-10-10 22:03:03 +00:00
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2020-12-16 07:37:30 +00:00
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输入图`[[0, 1, 0, 0], [1, 0, 0, 0], [0, 0, 0, 1], [0, 0, 1, 0]]` ,起始节点为`0`应该返回一个`0`和`1`的数组。
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2018-10-10 22:03:03 +00:00
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2020-12-16 07:37:30 +00:00
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```js
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assert.sameMembers(
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(function () {
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var graph = [
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[0, 1, 0, 0],
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[1, 0, 0, 0],
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[0, 0, 0, 1],
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[0, 0, 1, 0]
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];
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return dfs(graph, 0);
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})(),
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[0, 1]
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);
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```
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2018-10-10 22:03:03 +00:00
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2020-12-16 07:37:30 +00:00
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输入图`[[0, 1, 0, 0], [1, 0, 0, 0], [0, 0, 0, 1], [0, 0, 1, 0]]` ,起始节点为`0`应该返回一个包含两个元素的数组。
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2018-10-10 22:03:03 +00:00
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```js
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2020-12-16 07:37:30 +00:00
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assert(
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(function () {
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var graph = [
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[0, 1, 0, 0],
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[1, 0, 0, 0],
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[0, 0, 0, 1],
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[0, 0, 1, 0]
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];
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return dfs(graph, 0);
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})().length === 2
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);
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2018-10-10 22:03:03 +00:00
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```
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2020-08-13 15:24:35 +00:00
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2020-12-16 07:37:30 +00:00
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# --solutions--
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