# Why it work at OJ but not my own computer? ->IndexError: list assignment index out of range

• Anyone could help me to solve this problem?

nums1[end] = nums2[l2], IndexError: list assignment index out of range

``````def merge(self, A, m, B, n):
"""
:type nums1: List[int]
:type m: int
:type nums2: List[int]
:type n: int
:rtype: void Do not return anything, modify nums1 in-place instead.
"""
l1, l2, end = m - 1, n - 1, m + n - 1
while l1 >= 0 and l2 >= 0:
if nums2[l2] > nums1[l1]:
nums1[end] = nums2[l2]
l2 -= 1
else:
nums1[end] = nums1[l1]
l1 -= 1
end -= 1
if l1 < 0:
nums1[:l2 + 1] = nums2[:l2 + 1]``````

• I am facing the same issue. Can anyone help us? Thanks in advance.

• The notes of this question on Leetcode said

"You may assume that nums1 has enough space (size that is greater or
equal to m + n) to hold additional elements from nums2."

When you run the code on your own computer, the input nums1 should be long enough. For example, you try call merge([1,2,3,4,9,0,0,0], 5, [5,6,7], 3), it works, the output is [1, 2, 3, 4, 5, 6, 7, 9]. Although the length of nums1 is 8(in order to hold all numbers from two arrays), m is still 5. So it works on your own computer if your input follows the Leetcode assume.

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