import sys

n, k = map(int, sys.stdin.readline().split())
for i in range(n):
    for j in range(n):
        if i == j:
            print(k, end=' ')
        else:
            print(0, end=' ')
    print()

直接k×n阶单位矩阵，也就是\left[ \begin{matrix}k & 0 & ... & 0\\ 0 & k & ... & 0\\ ... & ... & ⋱ & 0\\ 0 & 0 & ... & k\\ \end{matrix} \right]