一夜无解，痛苦，遂拜倒于灵神门下，妄做狂徒也！

. - 力扣（LeetCode）

灵神秒解如下：

class NumMatrix:     #二维初始矩阵     def __init__(self, matrix: List[List[int]]):        m=len(matrix)        n=len(matrix[0])        #扩充一下，防止数组越界        sum=[[0]*(n+1) for _ in range(m+1)]        for i in range(m):            for j in range(n):              sum[i+1][j+1]=sum[i+1][j]+sum[i][j+1]-sum[i][j]+matrix[i][j]        self.sum=sum      #子矩阵计算和     def sumRegion(self, row1: int, col1: int, row2: int, col2: int) -> int:        return self.sum[row2+1][col2+1]-self.sum[row2+1][col1]-self.sum[row1][col2+1]+self.sum[row1][col1]