Algorithm
Problem Name: 842. Split Array into Fibonacci Sequence
You are given a string of digits num, such as "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] < 231, (that is, each integer fits in a 32-bit signed integer type),f.length >= 3, andf[i] + f[i + 1] == f[i + 2]for all0 <= i < f.length - 2.
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 num, or return [] if it cannot be done.
Example 1:
Input: num = "1101111" Output: [11,0,11,11] Explanation: The output [110, 1, 111] would also be accepted.
Example 2:
Input: num = "112358130" Output: [] Explanation: The task is impossible.
Example 3:
Input: num = "0123" Output: [] Explanation: Leading zeroes are not allowed, so "01", "2", "3" is not valid.
Constraints:
1 <= num.length <= 200numcontains only digits.
Code Examples
#1 Code Example with Python Programming
Code -
Python Programming
class Solution:
def splitIntoFibonacci(self, S):
def getStarter():
arr = []
for i in range(1, len(S) - 1):
for j in range(i + 1, len(S)):
s1, s2 = S[:i], S[i:j]
if (s1[0] == "0" and len(s1) > 1) or (s2[0] == "0" and len(s2) > 1):
continue
arr.append((int(s1), int(s2), j))
return arr
def dfs(arr, i):
if i == len(S):
return arr
sm = arr[-2] + arr[-1]
l = len(str(sm))
new = int(S[i:i + l])
return new == sm and 0 <= sm <= mx and dfs(arr + [new], i + l)
q, mx = getStarter(), 2 ** 31 - 1
for p1, p2, i in q:
seq = dfs([p1, p2], i)
if seq:
return seq
return []
Input
num = "1101111"
Output
[11,0,11,11]