Leetcode_Python 304 二维区域和检索 - 矩阵不可变

class NumMatrix(object):
    def __init__(self, matrix):
        """
        :type matrix: List[List[int]]
        """
        self.matrix = matrix
    def sumRegion(self, row1, col1, row2, col2):
        """
        :type row1: int
        :type col1: int
        :type row2: int
        :type col2: int
        :rtype: int
        """
        self.sums = 0 
        for i in range(row1,row2 + 1):
            self.sums += sum(self.matrix[i][col1:col2+1])
        return self.sums