Minimum Path Sum LeetCode solution in Python

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class Solution:
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    def minPathSum(self, grid: List[List[int]]) -> int:
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        prev = [0] * len(grid[0])
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        for i in range(len(grid)):
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            temp = [0] * len(grid[0])
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            for j in range(len(grid[0])):
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                if i == 0 and j == 0:
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                    temp[j] = grid[i][j]
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                    continue
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                if i > 0:
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                    lft = grid[i][j] + prev[j]
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                else:
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                    lft = grid[i][j] + 1000
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                if j > 0:
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                    up = grid[i][j] + temp[j - 1]
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                else:
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                    up = grid[i][j] + 1000
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                temp[j] = min(up, lft)
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            prev = temp
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        return prev[-1]