{"id":34154,"date":"2024-11-01T09:24:52","date_gmt":"2024-11-01T09:24:52","guid":{"rendered":"http:\/\/atmokpo.com\/w\/?p=34154"},"modified":"2024-11-01T10:58:24","modified_gmt":"2024-11-01T10:58:24","slug":"c-coding-test-course-depth-first-search-2","status":"publish","type":"post","link":"https:\/\/atmokpo.com\/w\/34154\/","title":{"rendered":"C++ Coding Test Course, Depth First Search"},"content":{"rendered":"

<\/p>\n

1. Problem Description<\/h2>\n

The given problem is as follows:<\/p>\n

\n

Implement an algorithm to find the size of the largest group of consecutive 1s in a two-dimensional array (N x M) composed of integers. A group is defined as a subset of 1s that are connected vertically or horizontally. Additionally, non-consecutive 1s are treated as different groups.<\/p>\n

The size of the array (N, M) is between 1 and 100.<\/p>\n<\/blockquote>\n

2. Problem Analysis<\/h2>\n

This problem is about using graph search algorithms like DFS (Depth-First Search) or BFS (Breadth-First Search) to find connected components. It can be solved by counting the number of connected 1s and keeping track of the maximum size of the group.<\/p>\n

The input array can be represented in the following form:<\/p>\n

\n    1 0 0 1 1\n    1 1 0 0 0\n    0 0 1 1 1\n    0 1 0 0 0\n    1 1 1 0 0\n    <\/pre>\n
In this case, the size of the largest group will be 5.<\/p>\n
3. Approach<\/h2>\n
We need to use depth-first search to find and count connected 1s. DFS is stack-based and can be implemented either recursively or explicitly with a stack. The following are the steps to solve the problem:<\/p>\n
    \n
  1. Iterate through the two-dimensional array and execute DFS when a 1 is found.<\/li>\n
  2. In DFS, explore connected 1s by moving vertically and horizontally and increase the count.<\/li>\n
  3. After exploring, compare and update the maximum group size.<\/li>\n
  4. Once the exploration is complete, return the final maximum group size.<\/li>\n<\/ol>\n
    4. Code Implementation<\/h2>\n
    Below is the C++ code implementing the above approach:<\/p>\n
    \n#include \n#include \n#include \n\nusing namespace std;\n\nclass Solution {\npublic:\n    int N, M; \/\/ Size of the array\n    vector> directions{{-1, 0}, {1, 0}, {0, -1}, {0, 1}}; \/\/ Directions for up, down, left, right\n\n    \/\/ Implementation of DFS\n    int dfs(int x, int y, vector>& grid) {\n        if (x < 0 || x >= N || y < 0 || y >= M || grid[x][y] == 0) {\n            return 0; \/\/ Out of bounds or 0 case\n        }\n\n        grid[x][y] = 0; \/\/ Mark as visited\n        int count = 1; \/\/ Count current 1\n\n        \/\/ Recursive calls in four directions\n        for (const auto& dir : directions) {\n            count += dfs(x + dir[0], y + dir[1], grid);\n        }\n\n        return count;\n    }\n\n    int largestGroupSize(vector>& grid) {\n        N = grid.size();\n        M = grid[0].size();\n        int maxSize = 0;\n\n        for (int i = 0; i < N; i++) {\n            for (int j = 0; j < M; j++) {\n                if (grid[i][j] == 1) { \/\/ When 1 is found\n                    int groupSize = dfs(i, j, grid); \/\/ Call DFS\n                    maxSize = max(maxSize, groupSize); \/\/ Update maximum group size\n                }\n            }\n        }\n\n        return maxSize;\n    }\n};\n\nint main() {\n    Solution sol;\n    vector> grid = {\n        {1, 0, 0, 1, 1},\n        {1, 1, 0, 0, 0},\n        {0, 0, 1, 1, 1},\n        {0, 1, 0, 0, 0},\n        {1, 1, 1, 0, 0}\n    };\n\n    int result = sol.largestGroupSize(grid);\n    cout << \"Size of the largest group: \" << result << endl;\n    return 0;\n}\n<\/vector<\/vector<\/vector<\/vector<\/algorithm><\/vector><\/iostream><\/code><\/pre>\n
    5. Code Explanation<\/h2>\n
    The above C++ code is structured as follows:<\/p>\n
      \n
    1. Variable declaration:<\/strong> N<\/code> and M<\/code> store the size of the array, and directions<\/code> defines movement directions for up, down, left, and right.<\/li>\n
    2. DFS function:<\/strong> The dfs<\/code> function recursively counts the number of connected 1s starting from the current position. It checks for boundary conditions and visit status.<\/li>\n
    3. Main function:<\/strong> The largestGroupSize<\/code> function iterates through the entire array, calling DFS every time a 1 is found to calculate the group size. It updates the maximum size and returns the final result.<\/li>\n<\/ol>\n
      6. Testing and Results<\/h2>\n
      The above code can be tested with various cases. For example, we can change the size of groups or add new group structures to observe different results.<\/p>\n
      A successful result would be:<\/p>\n
      Size of the largest group: 5<\/code><\/pre>\n
      7. Time Complexity Analysis<\/h2>\n
      This algorithm has a time complexity of O(N * M) because each cell is visited once. The memory complexity is also O(N * M) due to the array and the recursive call stack.<\/p>\n
      8. Conclusion<\/h2>\n
      In this lecture, we solved the problem of finding the maximum group size of connected 1s using depth-first search. DFS is a very useful algorithm for pathfinding problems and connected component identification, and it can be utilized in many algorithmic problems.<\/p>\n
      Next, we will discuss BFS and tackle various application problems. Thank you!<\/p>\n
      <\/body><\/p>\n","protected":false},"excerpt":{"rendered":"
      1. Problem Description The given problem is as follows: Implement an algorithm to find the size of the largest group of consecutive 1s in a two-dimensional array (N x M) composed of integers. A group is defined as a subset of 1s that are connected vertically or horizontally. Additionally, non-consecutive 1s are treated as different … \ub354 \ubcf4\uae30 “C++ Coding Test Course, Depth First Search”<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[111],"tags":[],"class_list":["post-34154","post","type-post","status-publish","format-standard","hentry","category-c-coding-test-tutorials-2"],"yoast_head":"\nC++ Coding Test Course, Depth First Search - \ub77c\uc774\ube0c\uc2a4\ub9c8\ud2b8<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/atmokpo.com\/w\/34154\/\" \/>\n<meta property=\"og:locale\" content=\"ko_KR\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"C++ Coding Test Course, Depth First Search - \ub77c\uc774\ube0c\uc2a4\ub9c8\ud2b8\" \/>\n<meta property=\"og:description\" content=\"1. Problem Description The given problem is as follows: Implement an algorithm to find the size of the largest group of consecutive 1s in a two-dimensional array (N x M) composed of integers. A group is defined as a subset of 1s that are connected vertically or horizontally. Additionally, non-consecutive 1s are treated as different … \ub354 \ubcf4\uae30 "C++ Coding Test Course, Depth First Search"\" \/>\n<meta property=\"og:url\" content=\"https:\/\/atmokpo.com\/w\/34154\/\" \/>\n<meta property=\"og:site_name\" content=\"\ub77c\uc774\ube0c\uc2a4\ub9c8\ud2b8\" \/>\n<meta property=\"article:published_time\" content=\"2024-11-01T09:24:52+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2024-11-01T10:58:24+00:00\" \/>\n<meta name=\"author\" content=\"root\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:creator\" content=\"@bebubo4\" \/>\n<meta name=\"twitter:site\" content=\"@bebubo4\" \/>\n<meta name=\"twitter:label1\" content=\"\uae00\uc4f4\uc774\" \/>\n\t<meta name=\"twitter:data1\" content=\"root\" \/>\n\t<meta name=\"twitter:label2\" content=\"\uc608\uc0c1 \ub418\ub294 \ud310\ub3c5 \uc2dc\uac04\" \/>\n\t<meta name=\"twitter:data2\" content=\"2\ubd84\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\/\/schema.org\",\"@graph\":[{\"@type\":\"Article\",\"@id\":\"https:\/\/atmokpo.com\/w\/34154\/#article\",\"isPartOf\":{\"@id\":\"https:\/\/atmokpo.com\/w\/34154\/\"},\"author\":{\"name\":\"root\",\"@id\":\"https:\/\/atmokpo.com\/w\/#\/schema\/person\/91b6b3b138fbba0efb4ae64b1abd81d7\"},\"headline\":\"C++ Coding Test Course, Depth First Search\",\"datePublished\":\"2024-11-01T09:24:52+00:00\",\"dateModified\":\"2024-11-01T10:58:24+00:00\",\"mainEntityOfPage\":{\"@id\":\"https:\/\/atmokpo.com\/w\/34154\/\"},\"wordCount\":438,\"publisher\":{\"@id\":\"https:\/\/atmokpo.com\/w\/#organization\"},\"articleSection\":[\"C++ Coding Test Tutorials\"],\"inLanguage\":\"ko-KR\"},{\"@type\":\"WebPage\",\"@id\":\"https:\/\/atmokpo.com\/w\/34154\/\",\"url\":\"https:\/\/atmokpo.com\/w\/34154\/\",\"name\":\"C++ Coding Test Course, Depth First Search - \ub77c\uc774\ube0c\uc2a4\ub9c8\ud2b8\",\"isPartOf\":{\"@id\":\"https:\/\/atmokpo.com\/w\/#website\"},\"datePublished\":\"2024-11-01T09:24:52+00:00\",\"dateModified\":\"2024-11-01T10:58:24+00:00\",\"breadcrumb\":{\"@id\":\"https:\/\/atmokpo.com\/w\/34154\/#breadcrumb\"},\"inLanguage\":\"ko-KR\",\"potentialAction\":[{\"@type\":\"ReadAction\",\"target\":[\"https:\/\/atmokpo.com\/w\/34154\/\"]}]},{\"@type\":\"BreadcrumbList\",\"@id\":\"https:\/\/atmokpo.com\/w\/34154\/#breadcrumb\",\"itemListElement\":[{\"@type\":\"ListItem\",\"position\":1,\"name\":\"\ud648\",\"item\":\"https:\/\/atmokpo.com\/w\/en\/\"},{\"@type\":\"ListItem\",\"position\":2,\"name\":\"C++ Coding Test Course, Depth First Search\"}]},{\"@type\":\"WebSite\",\"@id\":\"https:\/\/atmokpo.com\/w\/#website\",\"url\":\"https:\/\/atmokpo.com\/w\/\",\"name\":\"\ub77c\uc774\ube0c\uc2a4\ub9c8\ud2b8\",\"description\":\"\",\"publisher\":{\"@id\":\"https:\/\/atmokpo.com\/w\/#organization\"},\"potentialAction\":[{\"@type\":\"SearchAction\",\"target\":{\"@type\":\"EntryPoint\",\"urlTemplate\":\"https:\/\/atmokpo.com\/w\/?s={search_term_string}\"},\"query-input\":{\"@type\":\"PropertyValueSpecification\",\"valueRequired\":true,\"valueName\":\"search_term_string\"}}],\"inLanguage\":\"ko-KR\"},{\"@type\":\"Organization\",\"@id\":\"https:\/\/atmokpo.com\/w\/#organization\",\"name\":\"\ub77c\uc774\ube0c\uc2a4\ub9c8\ud2b8\",\"url\":\"https:\/\/atmokpo.com\/w\/\",\"logo\":{\"@type\":\"ImageObject\",\"inLanguage\":\"ko-KR\",\"@id\":\"https:\/\/atmokpo.com\/w\/#\/schema\/logo\/image\/\",\"url\":\"https:\/\/atmokpo.com\/w\/wp-content\/uploads\/2024\/11\/logo.png\",\"contentUrl\":\"https:\/\/atmokpo.com\/w\/wp-content\/uploads\/2024\/11\/logo.png\",\"width\":400,\"height\":400,\"caption\":\"\ub77c\uc774\ube0c\uc2a4\ub9c8\ud2b8\"},\"image\":{\"@id\":\"https:\/\/atmokpo.com\/w\/#\/schema\/logo\/image\/\"},\"sameAs\":[\"https:\/\/x.com\/bebubo4\"]},{\"@type\":\"Person\",\"@id\":\"https:\/\/atmokpo.com\/w\/#\/schema\/person\/91b6b3b138fbba0efb4ae64b1abd81d7\",\"name\":\"root\",\"image\":{\"@type\":\"ImageObject\",\"inLanguage\":\"ko-KR\",\"@id\":\"https:\/\/atmokpo.com\/w\/#\/schema\/person\/image\/\",\"url\":\"https:\/\/secure.gravatar.com\/avatar\/708197b41fc6435a7ce22d951b25d4a47e9e904270cb1f04682d4f025066f80c?s=96&d=mm&r=g\",\"contentUrl\":\"https:\/\/secure.gravatar.com\/avatar\/708197b41fc6435a7ce22d951b25d4a47e9e904270cb1f04682d4f025066f80c?s=96&d=mm&r=g\",\"caption\":\"root\"},\"sameAs\":[\"http:\/\/atmokpo.com\/w\"],\"url\":\"https:\/\/atmokpo.com\/w\/author\/root\/\"}]}<\/script>\n<!-- \/ Yoast SEO plugin. -->","yoast_head_json":{"title":"C++ Coding Test Course, Depth First Search - \ub77c\uc774\ube0c\uc2a4\ub9c8\ud2b8","robots":{"index":"index","follow":"follow","max-snippet":"max-snippet:-1","max-image-preview":"max-image-preview:large","max-video-preview":"max-video-preview:-1"},"canonical":"https:\/\/atmokpo.com\/w\/34154\/","og_locale":"ko_KR","og_type":"article","og_title":"C++ Coding Test Course, Depth First Search - \ub77c\uc774\ube0c\uc2a4\ub9c8\ud2b8","og_description":"1. Problem Description The given problem is as follows: Implement an algorithm to find the size of the largest group of consecutive 1s in a two-dimensional array (N x M) composed of integers. A group is defined as a subset of 1s that are connected vertically or horizontally. Additionally, non-consecutive 1s are treated as different … \ub354 \ubcf4\uae30 \"C++ Coding Test Course, Depth First Search\"","og_url":"https:\/\/atmokpo.com\/w\/34154\/","og_site_name":"\ub77c\uc774\ube0c\uc2a4\ub9c8\ud2b8","article_published_time":"2024-11-01T09:24:52+00:00","article_modified_time":"2024-11-01T10:58:24+00:00","author":"root","twitter_card":"summary_large_image","twitter_creator":"@bebubo4","twitter_site":"@bebubo4","twitter_misc":{"\uae00\uc4f4\uc774":"root","\uc608\uc0c1 \ub418\ub294 \ud310\ub3c5 \uc2dc\uac04":"2\ubd84"},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"Article","@id":"https:\/\/atmokpo.com\/w\/34154\/#article","isPartOf":{"@id":"https:\/\/atmokpo.com\/w\/34154\/"},"author":{"name":"root","@id":"https:\/\/atmokpo.com\/w\/#\/schema\/person\/91b6b3b138fbba0efb4ae64b1abd81d7"},"headline":"C++ Coding Test Course, Depth First Search","datePublished":"2024-11-01T09:24:52+00:00","dateModified":"2024-11-01T10:58:24+00:00","mainEntityOfPage":{"@id":"https:\/\/atmokpo.com\/w\/34154\/"},"wordCount":438,"publisher":{"@id":"https:\/\/atmokpo.com\/w\/#organization"},"articleSection":["C++ Coding Test Tutorials"],"inLanguage":"ko-KR"},{"@type":"WebPage","@id":"https:\/\/atmokpo.com\/w\/34154\/","url":"https:\/\/atmokpo.com\/w\/34154\/","name":"C++ Coding Test Course, Depth First Search - \ub77c\uc774\ube0c\uc2a4\ub9c8\ud2b8","isPartOf":{"@id":"https:\/\/atmokpo.com\/w\/#website"},"datePublished":"2024-11-01T09:24:52+00:00","dateModified":"2024-11-01T10:58:24+00:00","breadcrumb":{"@id":"https:\/\/atmokpo.com\/w\/34154\/#breadcrumb"},"inLanguage":"ko-KR","potentialAction":[{"@type":"ReadAction","target":["https:\/\/atmokpo.com\/w\/34154\/"]}]},{"@type":"BreadcrumbList","@id":"https:\/\/atmokpo.com\/w\/34154\/#breadcrumb","itemListElement":[{"@type":"ListItem","position":1,"name":"\ud648","item":"https:\/\/atmokpo.com\/w\/en\/"},{"@type":"ListItem","position":2,"name":"C++ Coding Test Course, Depth First Search"}]},{"@type":"WebSite","@id":"https:\/\/atmokpo.com\/w\/#website","url":"https:\/\/atmokpo.com\/w\/","name":"\ub77c\uc774\ube0c\uc2a4\ub9c8\ud2b8","description":"","publisher":{"@id":"https:\/\/atmokpo.com\/w\/#organization"},"potentialAction":[{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https:\/\/atmokpo.com\/w\/?s={search_term_string}"},"query-input":{"@type":"PropertyValueSpecification","valueRequired":true,"valueName":"search_term_string"}}],"inLanguage":"ko-KR"},{"@type":"Organization","@id":"https:\/\/atmokpo.com\/w\/#organization","name":"\ub77c\uc774\ube0c\uc2a4\ub9c8\ud2b8","url":"https:\/\/atmokpo.com\/w\/","logo":{"@type":"ImageObject","inLanguage":"ko-KR","@id":"https:\/\/atmokpo.com\/w\/#\/schema\/logo\/image\/","url":"https:\/\/atmokpo.com\/w\/wp-content\/uploads\/2024\/11\/logo.png","contentUrl":"https:\/\/atmokpo.com\/w\/wp-content\/uploads\/2024\/11\/logo.png","width":400,"height":400,"caption":"\ub77c\uc774\ube0c\uc2a4\ub9c8\ud2b8"},"image":{"@id":"https:\/\/atmokpo.com\/w\/#\/schema\/logo\/image\/"},"sameAs":["https:\/\/x.com\/bebubo4"]},{"@type":"Person","@id":"https:\/\/atmokpo.com\/w\/#\/schema\/person\/91b6b3b138fbba0efb4ae64b1abd81d7","name":"root","image":{"@type":"ImageObject","inLanguage":"ko-KR","@id":"https:\/\/atmokpo.com\/w\/#\/schema\/person\/image\/","url":"https:\/\/secure.gravatar.com\/avatar\/708197b41fc6435a7ce22d951b25d4a47e9e904270cb1f04682d4f025066f80c?s=96&d=mm&r=g","contentUrl":"https:\/\/secure.gravatar.com\/avatar\/708197b41fc6435a7ce22d951b25d4a47e9e904270cb1f04682d4f025066f80c?s=96&d=mm&r=g","caption":"root"},"sameAs":["http:\/\/atmokpo.com\/w"],"url":"https:\/\/atmokpo.com\/w\/author\/root\/"}]}},"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"jetpack-related-posts":[],"_links":{"self":[{"href":"https:\/\/atmokpo.com\/w\/wp-json\/wp\/v2\/posts\/34154","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/atmokpo.com\/w\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/atmokpo.com\/w\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/atmokpo.com\/w\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/atmokpo.com\/w\/wp-json\/wp\/v2\/comments?post=34154"}],"version-history":[{"count":1,"href":"https:\/\/atmokpo.com\/w\/wp-json\/wp\/v2\/posts\/34154\/revisions"}],"predecessor-version":[{"id":34155,"href":"https:\/\/atmokpo.com\/w\/wp-json\/wp\/v2\/posts\/34154\/revisions\/34155"}],"wp:attachment":[{"href":"https:\/\/atmokpo.com\/w\/wp-json\/wp\/v2\/media?parent=34154"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/atmokpo.com\/w\/wp-json\/wp\/v2\/categories?post=34154"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/atmokpo.com\/w\/wp-json\/wp\/v2\/tags?post=34154"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}