问空白断言错误-找不到问题区域
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Stack Overflow用户

提问于 2021-08-30 11:33:10

回答 1查看 47关注 0票数 0

我正在编写一个使用二进制搜索的程序来查找两个列表的交叉索引。我已经编写了整个程序，但是当我尝试返回findCrossoverIndexHelper(x，y，0，len(y))时，我遇到了一个空白断言错误。如果有人能指出断言错误在哪里，或者我如何追溯错误，我将不胜感激。

谢谢你的帮助。

#First write a "helper" function with two extra parameters
# left, right that describes the search region as shown below
def findCrossoverIndexHelper(x, y, left, right):
    # Note: Output index i such that 
    #         left <= i <= right
    #         x[i] <= y[i]
    # First, Write down our invariants as assertions here
    assert(len(x) == len(y))
    assert(left >= 0)
    assert(left <= right-1)
    assert(right < len(x))
    # Here is the key property we would like to maintain.
    assert(x[left] > y[left])
    assert(x[right] < y[right])
    
    mid = (left+right)//2
    # if middle index = left then we found crossover
    if(mid == left):
        return mid
    # if middle index elements has x > y
    # then we need to change left to mid
    if(x[mid] >= y[mid]):
        return findCrossoverIndexHelper(x, y, mid, right)
    # if middle index elements has x < y
    # then we need to change right to mid
    elif (x[mid] < y[mid]):
        return findCrossoverIndexHelper(x, y, left, mid)

#Define the function findCrossoverIndex that will 
# call the helper function findCrossoverIndexHelper
def findCrossoverIndex(x, y):
    assert(len(x) == len(y))
    assert(x[0] > y[0])
    n = len(x)
    assert(x[n-1] < y[n-1]) # Note: this automatically ensures n >= 2 why?
    return findCrossoverIndexHelper(x, y, 0,len(y))

BEGIN TEST CASES
j1 = findCrossoverIndex([0, 1, 2, 3, 4, 5, 6, 7], [-2, 0, 4, 5, 6, 7, 8, 9])
print('j1 = %d' % j1)
assert j1 == 1, "Test Case # 1 Failed"

j2 = findCrossoverIndex([0, 1, 2, 3, 4, 5, 6, 7], [-2, 0, 4, 4.2, 4.3, 4.5, 8, 9])
print('j2 = %d' % j2)
assert j2 == 1 or j2 == 5, "Test Case # 2 Failed"

j3 = findCrossoverIndex([0, 1], [-10, 10])
print('j3 = %d' % j3)
assert j3 == 0, "Test Case # 3 failed"

j4 = findCrossoverIndex([0,1, 2, 3], [-10, -9, -8, 5])
print('j4 = %d' % j4)
assert j4 == 2, "Test Case # 4 failed"

print('Congratulations: all test cases passed - 10 points')
#END TEST CASES

AssertionError
---------------------------------------------------------------------------
AssertionError                            Traceback (most recent call last)
<ipython-input-257-87cacde37648> in <module>
      1 # BEGIN TEST CASES
----> 2 j1 = findCrossoverIndex([0, 1, 2, 3, 4, 5, 6, 7], [-2, 0, 4, 5, 6, 7, 8, 9])
      3 print('j1 = %d' % j1)
      4 assert j1 == 1, "Test Case # 1 Failed"
      5 

<ipython-input-256-d93a1b9d946e> in findCrossoverIndex(x, y)
      6     n = len(x)
      7     assert(x[n-1] < y[n-1]) # Note: this automatically ensures n >= 2 why?
----> 8     return findCrossoverIndexHelper(x, y, 0,len(y))

<ipython-input-255-3ece5541426f> in findCrossoverIndexHelper(x, y, left, right)
      9     assert(left >= 0)
     10     assert(left <= right-1)
---> 11     assert(right < len(x))
     12     # Here is the key property we would like to maintain.
     13     assert(x[left] > y[left])

AssertionError: