B
1
⋯
B
s
总和
A
1
n
11
⋯
n
1
s
n
1
⋅
⋮
⋮
⋮
A
r
n
r
1
⋯
n
r
s
n
r
⋅
总和
n
⋅
1
⋯
n
⋅
s
n