문제 링크

정답 :

def solution(n):
    matrix = [[1 if i == j else 0 for j in range(n)] for i in range(n)]
    
    return matrix

방법 1:

def solution(n):
    answer = [[0] * n for i in range(n)]
    for i in range(n):
			    answer[i][i] = 1
			    
    return answer