{"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":2147,"title":"Langston's Ant","description":"The \u003chttp://en.wikipedia.org/wiki/Langton%27s_ant Langston's Ant\u003e Challenge is to determine the number of Black squares after K Ant moves. \r\n\r\nAn infinite white board has an Ant at the center. Direction is not required.\r\n\r\nMovement and Affect:\r\n\r\n  1) At a white square, turn 90° right, White goes to Black, move forward one unit\r\n  2) At a black square, turn 90° left, Black goes to White, move forward one unit\r\n\r\nAfter a given number of moves how many Black squares are present. \r\n\r\n*Input:* K,  number of moves from 100 to 12000\r\n\r\n*Output:* BLK, number of Black squares\r\n\r\n*Example:* K=5, BLK=3  [00000;00010;00110]\r\n\r\n*Note:*  After 11000 moves a pattern emerges\r\n\r\n","description_html":"\u003cp\u003eThe \u003ca href = \"http://en.wikipedia.org/wiki/Langton%27s_ant\"\u003eLangston's Ant\u003c/a\u003e Challenge is to determine the number of Black squares after K Ant moves.\u003c/p\u003e\u003cp\u003eAn infinite white board has an Ant at the center. Direction is not required.\u003c/p\u003e\u003cp\u003eMovement and Affect:\u003c/p\u003e\u003cpre class=\"language-matlab\"\u003e1) At a white square, turn 90° right, White goes to Black, move forward one unit\r\n2) At a black square, turn 90° left, Black goes to White, move forward one unit\r\n\u003c/pre\u003e\u003cp\u003eAfter a given number of moves how many Black squares are present.\u003c/p\u003e\u003cp\u003e\u003cb\u003eInput:\u003c/b\u003e K,  number of moves from 100 to 12000\u003c/p\u003e\u003cp\u003e\u003cb\u003eOutput:\u003c/b\u003e BLK, number of Black squares\u003c/p\u003e\u003cp\u003e\u003cb\u003eExample:\u003c/b\u003e K=5, BLK=3  [00000;00010;00110]\u003c/p\u003e\u003cp\u003e\u003cb\u003eNote:\u003c/b\u003e  After 11000 moves a pattern emerges\u003c/p\u003e","function_template":"function BLK=Langston_Ant(L)\r\n BLK=0;\r\nend","test_suite":"%%\r\nassert(isequal(Langston_Ant(100),20))\r\n%%\r\nassert(isequal(Langston_Ant(200),40))\r\n%%\r\nassert(isequal(Langston_Ant(300),48))\r\n%%\r\nassert(isequal(Langston_Ant(400),62))\r\n%%\r\nassert(isequal(Langston_Ant(500),62))\r\n%%\r\nassert(isequal(Langston_Ant(600),72))\r\n%%\r\nassert(isequal(Langston_Ant(700),80))\r\n%%\r\nassert(isequal(Langston_Ant(800),96))\r\n%%\r\nassert(isequal(Langston_Ant(900),108))\r\n%%\r\nassert(isequal(Langston_Ant(1000),118))\r\n%%\r\nassert(isequal(Langston_Ant(12000),952))\r\n","published":true,"deleted":false,"likes_count":7,"comments_count":0,"created_by":3097,"edited_by":null,"edited_at":null,"deleted_by":null,"deleted_at":null,"solvers_count":40,"test_suite_updated_at":null,"rescore_all_solutions":false,"group_id":1,"created_at":"2014-02-01T22:20:21.000Z","updated_at":"2026-05-25T03:47:34.000Z","published_at":"2014-02-01T22:35:43.000Z","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\u003eThe\u003c/w:t\u003e\u003c/w:r\u003e\u003cw:r\u003e\u003cw:t\u003e \u003c/w:t\u003e\u003c/w:r\u003e\u003cw:hyperlink w:docLocation=\\\"http://en.wikipedia.org/wiki/Langton%27s_ant\\\"\u003e\u003cw:r\u003e\u003cw:t\u003eLangston's Ant\u003c/w:t\u003e\u003c/w:r\u003e\u003c/w:hyperlink\u003e\u003cw:r\u003e\u003cw:t\u003e Challenge is to determine the number of Black squares after K Ant moves.\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\u003eAn infinite white board has an Ant at the center. Direction is not required.\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\u003eMovement and Affect:\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[1) At a white square, turn 90° right, White goes to Black, move forward one unit\\n2) At a black square, turn 90° left, Black goes to White, move forward one unit]]\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\u003eAfter a given number of moves how many Black squares are present.\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:rPr\u003e\u003cw:b/\u003e\u003c/w:rPr\u003e\u003cw:t\u003eInput:\u003c/w:t\u003e\u003c/w:r\u003e\u003cw:r\u003e\u003cw:t\u003e K, number of moves from 100 to 12000\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:rPr\u003e\u003cw:b/\u003e\u003c/w:rPr\u003e\u003cw:t\u003eOutput:\u003c/w:t\u003e\u003c/w:r\u003e\u003cw:r\u003e\u003cw:t\u003e BLK, number of Black squares\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:rPr\u003e\u003cw:b/\u003e\u003c/w:rPr\u003e\u003cw:t\u003eExample:\u003c/w:t\u003e\u003c/w:r\u003e\u003cw:r\u003e\u003cw:t\u003e K=5, BLK=3 [00000;00010;00110]\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:rPr\u003e\u003cw:b/\u003e\u003c/w:rPr\u003e\u003cw:t\u003eNote:\u003c/w:t\u003e\u003c/w:r\u003e\u003cw:r\u003e\u003cw:t\u003e After 11000 moves a pattern emerges\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":2147,"title":"Langston's Ant","description":"The \u003chttp://en.wikipedia.org/wiki/Langton%27s_ant Langston's Ant\u003e Challenge is to determine the number of Black squares after K Ant moves. \r\n\r\nAn infinite white board has an Ant at the center. Direction is not required.\r\n\r\nMovement and Affect:\r\n\r\n  1) At a white square, turn 90° right, White goes to Black, move forward one unit\r\n  2) At a black square, turn 90° left, Black goes to White, move forward one unit\r\n\r\nAfter a given number of moves how many Black squares are present. \r\n\r\n*Input:* K,  number of moves from 100 to 12000\r\n\r\n*Output:* BLK, number of Black squares\r\n\r\n*Example:* K=5, BLK=3  [00000;00010;00110]\r\n\r\n*Note:*  After 11000 moves a pattern emerges\r\n\r\n","description_html":"\u003cp\u003eThe \u003ca href = \"http://en.wikipedia.org/wiki/Langton%27s_ant\"\u003eLangston's Ant\u003c/a\u003e Challenge is to determine the number of Black squares after K Ant moves.\u003c/p\u003e\u003cp\u003eAn infinite white board has an Ant at the center. Direction is not required.\u003c/p\u003e\u003cp\u003eMovement and Affect:\u003c/p\u003e\u003cpre class=\"language-matlab\"\u003e1) At a white square, turn 90° right, White goes to Black, move forward one unit\r\n2) At a black square, turn 90° left, Black goes to White, move forward one unit\r\n\u003c/pre\u003e\u003cp\u003eAfter a given number of moves how many Black squares are present.\u003c/p\u003e\u003cp\u003e\u003cb\u003eInput:\u003c/b\u003e K,  number of moves from 100 to 12000\u003c/p\u003e\u003cp\u003e\u003cb\u003eOutput:\u003c/b\u003e BLK, number of Black squares\u003c/p\u003e\u003cp\u003e\u003cb\u003eExample:\u003c/b\u003e K=5, BLK=3  [00000;00010;00110]\u003c/p\u003e\u003cp\u003e\u003cb\u003eNote:\u003c/b\u003e  After 11000 moves a pattern emerges\u003c/p\u003e","function_template":"function BLK=Langston_Ant(L)\r\n BLK=0;\r\nend","test_suite":"%%\r\nassert(isequal(Langston_Ant(100),20))\r\n%%\r\nassert(isequal(Langston_Ant(200),40))\r\n%%\r\nassert(isequal(Langston_Ant(300),48))\r\n%%\r\nassert(isequal(Langston_Ant(400),62))\r\n%%\r\nassert(isequal(Langston_Ant(500),62))\r\n%%\r\nassert(isequal(Langston_Ant(600),72))\r\n%%\r\nassert(isequal(Langston_Ant(700),80))\r\n%%\r\nassert(isequal(Langston_Ant(800),96))\r\n%%\r\nassert(isequal(Langston_Ant(900),108))\r\n%%\r\nassert(isequal(Langston_Ant(1000),118))\r\n%%\r\nassert(isequal(Langston_Ant(12000),952))\r\n","published":true,"deleted":false,"likes_count":7,"comments_count":0,"created_by":3097,"edited_by":null,"edited_at":null,"deleted_by":null,"deleted_at":null,"solvers_count":40,"test_suite_updated_at":null,"rescore_all_solutions":false,"group_id":1,"created_at":"2014-02-01T22:20:21.000Z","updated_at":"2026-05-25T03:47:34.000Z","published_at":"2014-02-01T22:35:43.000Z","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\u003eThe\u003c/w:t\u003e\u003c/w:r\u003e\u003cw:r\u003e\u003cw:t\u003e \u003c/w:t\u003e\u003c/w:r\u003e\u003cw:hyperlink w:docLocation=\\\"http://en.wikipedia.org/wiki/Langton%27s_ant\\\"\u003e\u003cw:r\u003e\u003cw:t\u003eLangston's Ant\u003c/w:t\u003e\u003c/w:r\u003e\u003c/w:hyperlink\u003e\u003cw:r\u003e\u003cw:t\u003e Challenge is to determine the number of Black squares after K Ant moves.\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\u003eAn infinite white board has an Ant at the center. Direction is not required.\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\u003eMovement and Affect:\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[1) At a white square, turn 90° right, White goes to Black, move forward one unit\\n2) At a black square, turn 90° left, Black goes to White, move forward one unit]]\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\u003eAfter a given number of moves how many Black squares are present.\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:rPr\u003e\u003cw:b/\u003e\u003c/w:rPr\u003e\u003cw:t\u003eInput:\u003c/w:t\u003e\u003c/w:r\u003e\u003cw:r\u003e\u003cw:t\u003e K, number of moves from 100 to 12000\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:rPr\u003e\u003cw:b/\u003e\u003c/w:rPr\u003e\u003cw:t\u003eOutput:\u003c/w:t\u003e\u003c/w:r\u003e\u003cw:r\u003e\u003cw:t\u003e BLK, number of Black squares\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:rPr\u003e\u003cw:b/\u003e\u003c/w:rPr\u003e\u003cw:t\u003eExample:\u003c/w:t\u003e\u003c/w:r\u003e\u003cw:r\u003e\u003cw:t\u003e K=5, BLK=3 [00000;00010;00110]\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:rPr\u003e\u003cw:b/\u003e\u003c/w:rPr\u003e\u003cw:t\u003eNote:\u003c/w:t\u003e\u003c/w:r\u003e\u003cw:r\u003e\u003cw:t\u003e After 11000 moves a pattern emerges\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\"}]}"}],"errors":[],"facets":[[{"value":"Logic","count":1,"selected":false}],[{"value":"medium","count":1,"selected":false}]],"term":"tag:\"turing machine\"","page":1,"per_page":50,"sort":"map(difficulty_value,0,0,999) asc"}}