Given a string S of digits, such as S = "123456579", we can split it into a Fibonacci-like sequence [123, 456, 579].
Formally, a Fibonacci-like sequence is a list F of non-negative integers such that:
- 0 <= F[i] <= 2^31 - 1, (that is, each integer fits a 32-bit signed integer type);
- F.length >= 3;
- and F[i] + F[i+1] = F[i+2] for all 0 <= i < F.length - 2.
Also, note that when splitting the string into pieces, each piece must not have extra leading zeroes, except if the piece is the number 0 itself.
Return any Fibonacci-like sequence split from S, or return [] if it cannot be done.
Example 1:
Input: "123456579"
Output: [123,456,579]
Example 2:
Input: "11235813"
Output: [1,1,2,3,5,8,13]
Example 3:
Input: "112358130"
Output: []
Explanation: The task is impossible.
Example 4:
Input: "0123"
Output: []
Explanation: Leading zeroes are not allowed, so "01", "2", "3" is not valid.
Example 5:
Input: "1101111"
Output: [110, 1, 111]
Explanation: The output [11, 0, 11, 11] would also be accepted.
Note:
- 1 <= S.length <= 200
- S contains only digits.
class Solution:
def splitIntoFibonacci(self, S):
"""
:type S: str
:rtype: List[int]
"""
MAX = 2**31-1
if len(S)<=2:
return []
def judge(s): #judge a string valid or not
if len(s)==1:
return True
if len(s)==0:
return False
if s[0]=='0':
return False
return True
def solve(i,j,res): #judge this method vaild or not
res = []
a,b = S[:i],S[i:j]
if judge(a) is False or judge(b) is False:
return []
n1,n2 = int(a),int(b)
if n1>MAX or n2>MAX:
return []
# print(n1,n2)
res.append(n1)
res.append(n2)
while True:
n3 = n1 + n2
res.append(n3)
c = str(n3)
if j+len(c)>len(S) or n3!=int(S[j:j+len(c)]) or n3>MAX:
return []
if j+len(c)==len(S):
return res
n1 = n2
n2 = n3
j = j+len(c)
# print('n2:',n2,'n1:',n1,'j:',j)
for i in range(1,len(S)//2+1):
for j in range(i+1,len(S)):
# print(i,j)
res = solve(i,j,[])
if len(res)>0:
return res
return []一次过