{"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":288,"title":"Construct a string from letters and counts","description":"Given two input arrays like this:\r\n    [5,3,1]\r\n    ['a','b','c']\r\n\r\nOutput a string that contains each letter the specified number of times, e.g.:\r\n\r\n    'aaaaabbbc'\r\n\r\nIf given an invalid input (for example, a negative number), output the string 'ERROR'.","description_html":"\u003cp\u003eGiven two input arrays like this:\r\n    [5,3,1]\r\n    ['a','b','c']\u003c/p\u003e\u003cp\u003eOutput a string that contains each letter the specified number of times, e.g.:\u003c/p\u003e\u003cpre\u003e    'aaaaabbbc'\u003c/pre\u003e\u003cp\u003eIf given an invalid input (for example, a negative number), output the string 'ERROR'.\u003c/p\u003e","function_template":"function y = construct_string(lengths, letters)\r\n  y = 'ERROR';\r\nend\r\n","test_suite":"%%\r\nx = []; y = [];\r\ny_correct = 'ERROR';\r\nassert(isequal(construct_string(x,y),y_correct))\r\n%%\r\nx = [-1]; y = ['a'];\r\ny_correct = 'ERROR';\r\nassert(isequal(construct_string(x,y),y_correct))\r\n%%\r\nx = ['a']; y = [5];\r\ny_correct = 'ERROR';\r\nassert(isequal(construct_string(x,y),y_correct))\r\n%%\r\nr = 10+randi(20); x = [r 1]; y = 'ab';\r\ny_correct(1:r) = 'a'; y_correct(r+1) = 'b';\r\nassert(isequal(construct_string(x,y),y_correct))\r\n%%\r\nx = [5 4 3 2 1];\r\ny = '.#4a5';\r\ny_correct = '.....####444aa5';\r\nassert(isequal(construct_string(x,y),y_correct))\r\n\r\n%%\r\nx1 = [1 1 1 1 1 1];\r\ny = 'banana';\r\nassert(isequal(construct_string(x1,y),y))\r\n","published":true,"deleted":false,"likes_count":1,"comments_count":1,"created_by":78,"edited_by":null,"edited_at":null,"deleted_by":null,"deleted_at":null,"solvers_count":147,"test_suite_updated_at":"2012-02-08T19:06:38.000Z","rescore_all_solutions":false,"group_id":1,"created_at":"2012-02-08T17:07:24.000Z","updated_at":"2026-05-06T03:34:55.000Z","published_at":"2012-02-08T19:12:34.000Z","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\u003eGiven two input arrays like this: [5,3,1] ['a','b','c']\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\u003eOutput a string that contains each letter the specified number of times, e.g.:\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[    'aaaaabbbc']]\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\u003eIf given an invalid input (for example, a negative number), output the string 'ERROR'.\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":288,"title":"Construct a string from letters and counts","description":"Given two input arrays like this:\r\n    [5,3,1]\r\n    ['a','b','c']\r\n\r\nOutput a string that contains each letter the specified number of times, e.g.:\r\n\r\n    'aaaaabbbc'\r\n\r\nIf given an invalid input (for example, a negative number), output the string 'ERROR'.","description_html":"\u003cp\u003eGiven two input arrays like this:\r\n    [5,3,1]\r\n    ['a','b','c']\u003c/p\u003e\u003cp\u003eOutput a string that contains each letter the specified number of times, e.g.:\u003c/p\u003e\u003cpre\u003e    'aaaaabbbc'\u003c/pre\u003e\u003cp\u003eIf given an invalid input (for example, a negative number), output the string 'ERROR'.\u003c/p\u003e","function_template":"function y = construct_string(lengths, letters)\r\n  y = 'ERROR';\r\nend\r\n","test_suite":"%%\r\nx = []; y = [];\r\ny_correct = 'ERROR';\r\nassert(isequal(construct_string(x,y),y_correct))\r\n%%\r\nx = [-1]; y = ['a'];\r\ny_correct = 'ERROR';\r\nassert(isequal(construct_string(x,y),y_correct))\r\n%%\r\nx = ['a']; y = [5];\r\ny_correct = 'ERROR';\r\nassert(isequal(construct_string(x,y),y_correct))\r\n%%\r\nr = 10+randi(20); x = [r 1]; y = 'ab';\r\ny_correct(1:r) = 'a'; y_correct(r+1) = 'b';\r\nassert(isequal(construct_string(x,y),y_correct))\r\n%%\r\nx = [5 4 3 2 1];\r\ny = '.#4a5';\r\ny_correct = '.....####444aa5';\r\nassert(isequal(construct_string(x,y),y_correct))\r\n\r\n%%\r\nx1 = [1 1 1 1 1 1];\r\ny = 'banana';\r\nassert(isequal(construct_string(x1,y),y))\r\n","published":true,"deleted":false,"likes_count":1,"comments_count":1,"created_by":78,"edited_by":null,"edited_at":null,"deleted_by":null,"deleted_at":null,"solvers_count":147,"test_suite_updated_at":"2012-02-08T19:06:38.000Z","rescore_all_solutions":false,"group_id":1,"created_at":"2012-02-08T17:07:24.000Z","updated_at":"2026-05-06T03:34:55.000Z","published_at":"2012-02-08T19:12:34.000Z","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\u003eGiven two input arrays like this: [5,3,1] ['a','b','c']\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\u003eOutput a string that contains each letter the specified number of times, e.g.:\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[    'aaaaabbbc']]\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\u003eIf given an invalid input (for example, a negative number), output the string 'ERROR'.\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":"easy","count":1,"selected":false}]],"term":"tag:\"error-checking\"","page":1,"per_page":50,"sort":"map(difficulty_value,0,0,999) asc"}}