{"group":{"id":1,"name":"Community","lockable":false,"created_at":"2012-01-18T18:02:15.000Z","updated_at":"2026-05-26T00:16:20.000Z","description":"Problems submitted by members of the MATLAB Central community.","is_default":true,"created_by":161519,"badge_id":null,"featured":false,"trending":false,"solution_count_in_trending_period":0,"trending_last_calculated":"2026-05-26T00:00:00.000Z","image_id":null,"published":true,"community_created":false,"status_id":2,"is_default_group_for_player":false,"deleted_by":null,"deleted_at":null,"restored_by":null,"restored_at":null,"description_opc":null,"description_html":null,"published_at":null},"problems":[{"id":42800,"title":"house of cards","description":"How many cards do one need to build a house of cards with n stages? \r\nShort explanation:\r\n\r\n\r\n  /\\      2 cards for 1 stage\r\n     \r\n /_\\    7 cards for 2 stages\r\n/\\ /\\\r\n\r\n....","description_html":"\u003cp\u003eHow many cards do one need to build a house of cards with n stages? \r\nShort explanation:\u003c/p\u003e\u003cpre class=\"language-matlab\"\u003e/\\      2 cards for 1 stage\r\n\u003c/pre\u003e\u003cpre\u003e /_\\    7 cards for 2 stages\r\n/\\ /\\\u003c/pre\u003e\u003cp\u003e....\u003c/p\u003e","function_template":"function K = house_of_cards(n)\r\nK=2;\r\nend","test_suite":"%%\r\nn = 1;\r\nK_correct = 2;\r\nassert(isequal(house_of_cards(n),K_correct))\r\n\r\n%%\r\nn = 2;\r\nK_correct = 7;\r\nassert(isequal(house_of_cards(n),K_correct))\r\n\r\n%%\r\nn = 3;\r\nK_correct = 15;\r\nassert(isequal(house_of_cards(n),K_correct))\r\n\r\n%%\r\nn = 10;\r\nK_correct = 155;\r\nassert(isequal(house_of_cards(n),K_correct))\r\n\r\n%%\r\nn = 100;\r\nK_correct = 15050;\r\nassert(isequal(house_of_cards(n),K_correct))\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n","published":true,"deleted":false,"likes_count":3,"comments_count":2,"created_by":73322,"edited_by":null,"edited_at":null,"deleted_by":null,"deleted_at":null,"solvers_count":39,"test_suite_updated_at":"2016-04-15T12:28:41.000Z","rescore_all_solutions":false,"group_id":1,"created_at":"2016-04-15T09:23:08.000Z","updated_at":"2026-05-28T17:32:03.000Z","published_at":"2016-04-15T09:23:08.000Z","restored_at":null,"restored_by":null,"spam":false,"simulink":false,"admin_reviewed":false,"description_opc":"{\"relationships\":[{\"relationshipType\":\"http://schemas.mathworks.com/matlab/code/2013/relationships/document\",\"targetMode\":\"\",\"relationshipId\":\"rId1\",\"target\":\"/matlab/document.xml\"},{\"relationshipType\":\"http://schemas.mathworks.com/matlab/code/2013/relationships/output\",\"targetMode\":\"\",\"relationshipId\":\"rId2\",\"target\":\"/matlab/output.xml\"}],\"parts\":[{\"partUri\":\"/matlab/document.xml\",\"relationship\":[],\"contentType\":\"application/vnd.mathworks.matlab.code.document+xml\",\"content\":\"\u003c?xml version=\\\"1.0\\\" encoding=\\\"UTF-8\\\"?\u003e\\n\u003cw:document xmlns:w=\\\"http://schemas.openxmlformats.org/wordprocessingml/2006/main\\\"\u003e\u003cw:body\u003e\u003cw:p\u003e\u003cw:pPr\u003e\u003cw:pStyle w:val=\\\"text\\\"/\u003e\u003c/w:pPr\u003e\u003cw:r\u003e\u003cw:t\u003eHow many cards do one need to build a house of cards with n stages? Short explanation:\u003c/w:t\u003e\u003c/w:r\u003e\u003c/w:p\u003e\u003cw:p\u003e\u003cw:pPr\u003e\u003cw:pStyle w:val=\\\"code\\\"/\u003e\u003c/w:pPr\u003e\u003cw:r\u003e\u003cw:t\u003e\u003c![CDATA[/\\\\      2 cards for 1 stage\\n\\n /_\\\\    7 cards for 2 stages\\n/\\\\ /\\\\]]\u003e\u003c/w:t\u003e\u003c/w:r\u003e\u003c/w:p\u003e\u003cw:p\u003e\u003cw:pPr\u003e\u003cw:pStyle w:val=\\\"text\\\"/\u003e\u003c/w:pPr\u003e\u003cw:r\u003e\u003cw:t\u003e....\u003c/w:t\u003e\u003c/w:r\u003e\u003c/w:p\u003e\u003c/w:body\u003e\u003c/w:document\u003e\"},{\"partUri\":\"/matlab/output.xml\",\"contentType\":\"text/xml\",\"content\":\"\u003c?xml version=\\\"1.0\\\" encoding=\\\"UTF-8\\\" standalone=\\\"no\\\" ?\u003e\u003cembeddedOutputs\u003e\u003cmetaData\u003e\u003cevaluationState\u003emanual\u003c/evaluationState\u003e\u003clayoutState\u003ecode\u003c/layoutState\u003e\u003coutputStatus\u003eready\u003c/outputStatus\u003e\u003c/metaData\u003e\u003coutputArray type=\\\"array\\\"/\u003e\u003cregionArray type=\\\"array\\\"/\u003e\u003c/embeddedOutputs\u003e\"}]}"}],"problem_search":{"problems":[{"id":42800,"title":"house of cards","description":"How many cards do one need to build a house of cards with n stages? \r\nShort explanation:\r\n\r\n\r\n  /\\      2 cards for 1 stage\r\n     \r\n /_\\    7 cards for 2 stages\r\n/\\ /\\\r\n\r\n....","description_html":"\u003cp\u003eHow many cards do one need to build a house of cards with n stages? \r\nShort explanation:\u003c/p\u003e\u003cpre class=\"language-matlab\"\u003e/\\      2 cards for 1 stage\r\n\u003c/pre\u003e\u003cpre\u003e /_\\    7 cards for 2 stages\r\n/\\ /\\\u003c/pre\u003e\u003cp\u003e....\u003c/p\u003e","function_template":"function K = house_of_cards(n)\r\nK=2;\r\nend","test_suite":"%%\r\nn = 1;\r\nK_correct = 2;\r\nassert(isequal(house_of_cards(n),K_correct))\r\n\r\n%%\r\nn = 2;\r\nK_correct = 7;\r\nassert(isequal(house_of_cards(n),K_correct))\r\n\r\n%%\r\nn = 3;\r\nK_correct = 15;\r\nassert(isequal(house_of_cards(n),K_correct))\r\n\r\n%%\r\nn = 10;\r\nK_correct = 155;\r\nassert(isequal(house_of_cards(n),K_correct))\r\n\r\n%%\r\nn = 100;\r\nK_correct = 15050;\r\nassert(isequal(house_of_cards(n),K_correct))\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n","published":true,"deleted":false,"likes_count":3,"comments_count":2,"created_by":73322,"edited_by":null,"edited_at":null,"deleted_by":null,"deleted_at":null,"solvers_count":39,"test_suite_updated_at":"2016-04-15T12:28:41.000Z","rescore_all_solutions":false,"group_id":1,"created_at":"2016-04-15T09:23:08.000Z","updated_at":"2026-05-28T17:32:03.000Z","published_at":"2016-04-15T09:23:08.000Z","restored_at":null,"restored_by":null,"spam":false,"simulink":false,"admin_reviewed":false,"description_opc":"{\"relationships\":[{\"relationshipType\":\"http://schemas.mathworks.com/matlab/code/2013/relationships/document\",\"targetMode\":\"\",\"relationshipId\":\"rId1\",\"target\":\"/matlab/document.xml\"},{\"relationshipType\":\"http://schemas.mathworks.com/matlab/code/2013/relationships/output\",\"targetMode\":\"\",\"relationshipId\":\"rId2\",\"target\":\"/matlab/output.xml\"}],\"parts\":[{\"partUri\":\"/matlab/document.xml\",\"relationship\":[],\"contentType\":\"application/vnd.mathworks.matlab.code.document+xml\",\"content\":\"\u003c?xml version=\\\"1.0\\\" encoding=\\\"UTF-8\\\"?\u003e\\n\u003cw:document xmlns:w=\\\"http://schemas.openxmlformats.org/wordprocessingml/2006/main\\\"\u003e\u003cw:body\u003e\u003cw:p\u003e\u003cw:pPr\u003e\u003cw:pStyle w:val=\\\"text\\\"/\u003e\u003c/w:pPr\u003e\u003cw:r\u003e\u003cw:t\u003eHow many cards do one need to build a house of cards with n stages? 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