CMU 15-112 Spring 2019: Fundamentals of Programming and Computer Science
Check 5.4


  1. Check 5.4
    Write the function flatten2D(lst) that takes a 2D list of integers (possibly ragged!) and returns a new 1D list with the same elements row-by-row. For example, flatten2D([[1, 2, 3], [4, 5], [6, 7], [8]]) should return [1, 2, 3, 4, 5, 6, 7, 8]. We'll keep this simple and assume that every integer is nested inside of the inner lists, i.e. there are no elements such that type(lst[i])==int. There are also no empty lists.

    def flatten2D(lst): pass def testFlatten2D(): print("Testing flatten2D...", end="") a=[[1, 2], [4, 5]] assert(flatten2D(a)==[1,2,4,5]) a=[[1, 2, 3], [110, 112, 122], [6, 7, 8]] assert(flatten2D(a)==[1,2,3,110,112,122,6,7,8]) a=[[1, 2, 3], [4, 5], [6, 7], [8]] assert(flatten2D(a)==[1,2,3,4,5,6,7,8]) print("Passed.") testFlatten2D() import sys def set_certificate(certificate_div_id, certificate): document[certificate_div_id].textContent = certificate def get_student_code(student_code_div_id): raw_student_code = document[student_code_div_id].textContent return window.patchCodeToCheckTimeout(raw_student_code, 'check_timeout();'); class captureIO: def __init__(self): self.captured = [] def get_output(self): out = "" for c in self.captured: out += str(c) return out def write(self, data): self.captured.append(data) def flush(self): pass def test(student_code): exec(student_code) result = [] cases = [[[11, 14, 15, 4], [20, 11, 2], [9, 18, 10]], [[2, 6, 12, 10], [12, 16, 7, 9], [9, 4, 5, 13, 3]], [[12, 0, 1], [4, 10], [16, 18]], [[4], [20, 16, 16, 9], [11, 18, 8]], [[12], [17, 8, 14, 7], [1, 12, 19]], [[13, 12, 2, 18], [3, 13], [20, 19]], [[18, 3, 6, 9], [9, 3, 9, 0, 18], [0, 10, 16, 10, 16]], [[7, 13, 4], [20, 8, 0, 10, 2], [7, 16]], [[15, 16, 1, 15, 16], [7, 8, 11], [8, 2, 9]], [[1, 16, 13, 19], [2], [11, 0, 5]], [[16], [19, 13, 19, 2, 16], [3, 20, 10, 0]], [[4, 0, 4], [9, 7, 8, 3, 17], [1, 11, 15]], [[13, 5, 11, 7], [2], [13, 14]], [[17, 1, 11], [5, 14, 7, 11], [14, 4, 9, 2, 19]], [[13, 4, 4, 6, 7], [20], [16, 4, 12]], [[13, 19, 8, 8, 2], [6, 14, 4], [0]], [[11], [11, 7, 15], [3, 13, 9]], [[2, 1, 1, 15, 11], [7], [5, 0, 1, 10, 2]], [[13, 18, 7, 3], [11, 12, 15], [9, 0, 8, 10]], [[0, 5, 17, 7], [13, 10, 13], [12, 8, 16, 11]]] for lst in cases: result.append(flatten2D(lst)) return result def make_certificate(student_code_div_id, certificate_div_id): student_code = get_student_code(student_code_div_id) certificate = [] try: capture = captureIO() sys.stdout = capture sys.stderr = capture result = test(student_code) certificate.append((result, type(result))) set_certificate(certificate_div_id, str(certificate)) except: set_certificate(certificate_div_id, "error")

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