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author | Jack Sangdahl <[email protected]> | 2024-07-02 11:21:43 -0600 |
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committer | Jack Sangdahl <[email protected]> | 2024-07-02 11:21:43 -0600 |
commit | 723e7b2800616a3d0aca5b8d5deb6e0b59606a3c (patch) | |
tree | 7c5ccf6428ad786714b34c331f7719564455e1c2 /make_xor_segment_zero.py | |
parent | 1cb433cf3ef98dc8fbd7722a05c09668199d3c26 (diff) | |
download | leetcode-723e7b2800616a3d0aca5b8d5deb6e0b59606a3c.tar.gz leetcode-723e7b2800616a3d0aca5b8d5deb6e0b59606a3c.zip |
1787. make the xor of all segments equal to zero
Diffstat (limited to 'make_xor_segment_zero.py')
-rw-r--r-- | make_xor_segment_zero.py | 41 |
1 files changed, 41 insertions, 0 deletions
diff --git a/make_xor_segment_zero.py b/make_xor_segment_zero.py new file mode 100644 index 0000000..2174968 --- /dev/null +++ b/make_xor_segment_zero.py @@ -0,0 +1,41 @@ +# 1787. Make the XOR of All Segments Equal to Zero +import collections + +""" +given an array 'nums' and an integer 'k'. the xor of a segment '[left, +right]' where 'left <= right' is the xor of all the elements with indices +between 'left' and 'right', inclusive 'nums[left] xor nums[left + 1] xor ... +xor nums[right]'. return the minimum number of elements to change in the +array such that the 'xor' of all segments of size 'k' is equal to zero +""" + + +class Solution(object): + def minChanges(self, nums, k): + """ + :type nums: List[int] + :type k: int + :rtype: int + """ + m = 1 << 10 + freq = collections.defaultdict(collections.Counter) + for i, n in enumerate(nums): + freq[i % k][n] += 1 + dp = [[0] * m for _ in range(k + 1)] + for i in range(1, m): + dp[0][i] = -float("inf") + for i in range(1, k + 1): + max_row = max(dp[i - 1]) + for j in range(m): + for mask in freq[i - 1]: + dp[i][j] = max( + dp[i][j], max_row, dp[i - 1][j ^ mask] + freq[i - 1][mask] + ) + return len(nums) - dp[-1][0] + + +if __name__ == "__main__": + obj = Solution() + print(obj.minChanges(nums=[1, 2, 0, 3, 0], k=1)) + print(obj.minChanges(nums=[3, 4, 5, 2, 1, 7, 3, 4, 7], k=3)) + print(obj.minChanges(nums=[1, 2, 4, 1, 2, 5, 1, 2, 6], k=3)) |