The testcase I fail is

["NumMatrix","sumRegion","sumRegion","sumRegion"]

[[[[1],[-7]]],[0,0,0,0],[1,0,1,0],[0,0,1,0]]

I use python. Based on this format, the initial matrix is [[[1],[-7]]] (THREE parentheses pairs)

Why? The initial matrix should be List[List[int]]. So it should be [[1], [-7]] (just TWO

parentheses pairs)

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