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Format Depth-First Search algorithm for graphs (#13316)

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- Add dfn and code tags
- Add img-responsive to GIF image
- Use horizontal rule instead of "Instructions"
- Fix challenge tests and add working solution
- Add DFS challenge solution
- Add additional tests to thoroughly check answer
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Eric Leung
2017-02-18 11:58:03 -08:00
committed by mrugesh mohapatra
parent 79bb7ee21b
commit af549f8034
1 changed files with 19 additions and 12 deletions
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challenges/08-coding-interview-questions-and-take-home-assignments/coding-interview-data-structure-questions.json
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@ -2720,20 +2720,21 @@
"id": "587d825d367417b2b2512c96", "id": "587d825d367417b2b2512c96",
"title": "Depth-First Search", "title": "Depth-First Search",
"description": [ "description": [
"Similar to breadth-first search, here we will learn about another graph traversal algorithm called depth-first search.", "Similar to <dfn>breadth-first search</dfn>, here we will learn about another graph traversal algorithm called <dfn>depth-first search</dfn>.",
"Whereas the breadth-first search searches incremental edge lengths away from the source node, depth-first search first goes down a path of edges as far as it can.", "Whereas the breadth-first search searches incremental edge lengths away from the source node, <dfn>depth-first search</dfn> first goes down a path of edges as far as it can.",
"Once it reaches one end of a path, the search will backtrack to the last node with an un-visited edge path and continue searching.", "Once it reaches one end of a path, the search will backtrack to the last node with an un-visited edge path and continue searching.",
"Visually, this is what the algorithm is doing where the top node is the starting point of the search.", "Visually, this is what the algorithm is doing where the top node is the starting point of the search.",
"<img src='https://camo.githubusercontent.com/aaad9e39961daf34d967c616edeb50abf3bf1235/68747470733a2f2f75706c6f61642e77696b696d656469612e6f72672f77696b6970656469612f636f6d6d6f6e732f372f37662f44657074682d46697273742d5365617263682e676966'>", "<img class='img-responsive' src='https://camo.githubusercontent.com/aaad9e39961daf34d967c616edeb50abf3bf1235/68747470733a2f2f75706c6f61642e77696b696d656469612e6f72672f77696b6970656469612f636f6d6d6f6e732f372f37662f44657074682d46697273742d5365617263682e676966'>",
"A simple output of this algorithm is a list of nodes which are reachable from a given node. So when implementing this algorithm, you'll need to keep track of the nodes you visit.", "A simple output of this algorithm is a list of nodes which are reachable from a given node. So when implementing this algorithm, you'll need to keep track of the nodes you visit.",
"Instructions", "<hr>",
"Write a function dfs() that takes an undirected, adjacency matrix graph and a node label root as parameters. The node label will just be the numeric value of the node between 0 and n - 1, where n is the total number of nodes in the graph.", "Write a function <code>dfs()</code> that takes an undirected, adjacency matrix <code>graph</code> and a node label <code>root</code> as parameters. The node label will just be the numeric value of the node between <code>0</code> and <code>n - 1</code>, where <code>n</code> is the total number of nodes in the graph.",
"Your function should output an array of all nodes reachable from root." "Your function should output an array of all nodes reachable from <code>root</code>."
], ],
"challengeSeed": [ "challengeSeed": [
"function dfs(graph, root) {", "function dfs(graph, root) {",
" ", " ",
"};", "}",
"",
"var exDFSGraph = [", "var exDFSGraph = [",
" [0, 1, 0, 0],", " [0, 1, 0, 0],",
" [1, 0, 1, 0],", " [1, 0, 1, 0],",
@ -2743,14 +2744,20 @@
"console.log(dfs(exDFSGraph, 3));" "console.log(dfs(exDFSGraph, 3));"
], ],
"tests": [ "tests": [
"assert.deepEqual((function() { var graph = [[0, 1, 0, 0], [1, 0, 1, 0], [0, 1, 0, 1], [0, 0, 1, 0]]; return dfs(graph, 1);})(), [0, 1, 2, 3], 'message: The input graph <code>[[0, 1, 0, 0], [1, 0, 1, 0], [0, 1, 0, 1], [0, 0, 1, 0]]</code> with a start node of <code>1</code> should return <code>[0, 1, 2, 3]</code>.');", "assert.sameMembers((function() { var graph = [[0, 1, 0, 0], [1, 0, 1, 0], [0, 1, 0, 1], [0, 0, 1, 0]]; return dfs(graph, 1);})(), [0, 1, 2, 3], 'message: The input graph <code>[[0, 1, 0, 0], [1, 0, 1, 0], [0, 1, 0, 1], [0, 0, 1, 0]]</code> with a start node of <code>1</code> should return an array with <code>0</code>, <code>1</code>, <code>2</code>, and <code>3</code>.');",
"assert.deepEqual((function() { var graph = [[0, 1, 0, 0], [1, 0, 1, 0], [0, 1, 0, 0], [0, 0, 0, 0]]; return dfs(graph, 3);})(), [3], 'message: The input graph <code>[[0, 1, 0, 0], [1, 0, 1, 0], [0, 1, 0, 0], [0, 0, 0, 0]]</code> with a start node of <code>1</code> should return <code>[3]</code>.');", "assert((function() { var graph = [[0, 1, 0, 0], [1, 0, 1, 0], [0, 1, 0, 1], [0, 0, 1, 0]]; return dfs(graph, 1);})().length === 4, 'message: The input graph <code>[[0, 1, 0, 0], [1, 0, 1, 0], [0, 1, 0, 1], [0, 0, 1, 0]]</code> with a start node of <code>1</code> should return an array with four elements.');",
"assert.deepEqual((function() { var graph = [[0, 1, 0, 0], [1, 0, 0, 0], [0, 0, 0, 1], [0, 0, 1, 0]]; return dfs(graph, 3);})(), [2, 3], 'message: The input graph <code>[[0, 1, 0, 0], [1, 0, 0, 0], [0, 0, 0, 1], [0, 0, 1, 0]]</code> with a start node of <code>3</code> should return <code>[2, 3]</code>.');", "assert.sameMembers((function() { var graph = [[0, 1, 0, 0], [1, 0, 1, 0], [0, 1, 0, 0], [0, 0, 0, 0]]; return dfs(graph, 3);})(), [3], 'message: The input graph <code>[[0, 1, 0, 0], [1, 0, 1, 0], [0, 1, 0, 0], [0, 0, 0, 0]]</code> with a start node of <code>3</code> should return an array with <code>3</code>.');",
"assert.deepEqual((function() { var graph = [[0, 1, 0, 0], [1, 0, 0, 0], [0, 0, 0, 1], [0, 0, 1, 0]]; return dfs(graph, 0);})(), [0, 1], 'message: The input graph <code>[[0, 1, 0, 0], [1, 0, 0, 0], [0, 0, 0, 1], [0, 0, 1, 0]]</code> with a start node of <code>0</code> should return <code>[0, 1]</code>.');" "assert((function() { var graph = [[0, 1, 0, 0], [1, 0, 1, 0], [0, 1, 0, 0], [0, 0, 0, 0]]; return dfs(graph, 3);})().length === 1, 'message: The input graph <code>[[0, 1, 0, 0], [1, 0, 1, 0], [0, 1, 0, 0], [0, 0, 0, 0]]</code> with a start node of <code>3</code> should return an array with one element.');",
"assert.sameMembers((function() { var graph = [[0, 1, 0, 0], [1, 0, 0, 0], [0, 0, 0, 1], [0, 0, 1, 0]]; return dfs(graph, 3);})(), [2, 3], 'message: The input graph <code>[[0, 1, 0, 0], [1, 0, 0, 0], [0, 0, 0, 1], [0, 0, 1, 0]]</code> with a start node of <code>3</code> should return an array with <code>2</code> and <code>3</code>.');",
"assert((function() { var graph = [[0, 1, 0, 0], [1, 0, 0, 0], [0, 0, 0, 1], [0, 0, 1, 0]]; return dfs(graph, 3);})().length === 2, 'message: The input graph <code>[[0, 1, 0, 0], [1, 0, 0, 0], [0, 0, 0, 1], [0, 0, 1, 0]]</code> with a start node of <code>3</code> should return an array with two elements.');",
"assert.sameMembers((function() { var graph = [[0, 1, 0, 0], [1, 0, 0, 0], [0, 0, 0, 1], [0, 0, 1, 0]]; return dfs(graph, 0);})(), [0, 1], 'message: The input graph <code>[[0, 1, 0, 0], [1, 0, 0, 0], [0, 0, 0, 1], [0, 0, 1, 0]]</code> with a start node of <code>0</code> should return an array with <code>0</code> and <code>1</code>.');",
"assert((function() { var graph = [[0, 1, 0, 0], [1, 0, 0, 0], [0, 0, 0, 1], [0, 0, 1, 0]]; return dfs(graph, 0);})().length === 2, 'message: The input graph <code>[[0, 1, 0, 0], [1, 0, 0, 0], [0, 0, 0, 1], [0, 0, 1, 0]]</code> with a start node of <code>0</code> should return an array with two elements.');"
], ],
"type": "waypoint", "type": "waypoint",
"releasedOn": "Feb 17, 2017", "releasedOn": "Feb 17, 2017",
"solutions": [], "solutions": [
"function dfs(graph, root) { var stack = []; var tempV; var visited = []; var tempVNeighbors = []; stack.push(root); while (stack.length > 0) { tempV = stack.pop(); if (visited.indexOf(tempV) == -1) { visited.push(tempV); tempVNeighbors = graph[tempV]; for (var i = 0; i < tempVNeighbors.length; i++) { if (tempVNeighbors[i] == 1) { stack.push(i); }}}} return visited;}"
],
"challengeType": 1, "challengeType": 1,
"translations": {} "translations": {}
} }