백준)1,2,3 더하기

https://www.acmicpc.net/problem/9095

9095번: 1, 2, 3 더하기

 

 

a = int(input())

for i in range(a):
  b = int(input())
  if b == 1:
    print(1)
  elif b == 2:
    print(2)
  elif b == 3:
    print(4)
  else:
    arr = [0 for _ in range(b)]
    arr[0] = 1
    arr[1] = 2
    arr[2] = 4
    for j in range(3,len(arr)):
      arr[j] = arr[j-1] + arr[j-2] + arr[j-3]
  
    print(arr[b-1])