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 all0 <= 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 { public List<Integer> splitIntoFibonacci(String s) { List<Integer> ans = new ArrayList<>(); if (s == null || s.length() < 3) { return ans; } splitIntoFibonacciHelper(0, s, ans); return ans; } private boolean splitIntoFibonacciHelper(int start, String s, List<Integer> curr) { if (start >= s.length() && curr.size() >= 3) { return true; } for (int i = start; i < s.length(); i++) { if (s.charAt(start) == '0' && i > start) { break; } long num = Long.parseLong(s.substring(start, i + 1)); if (num > Integer.MAX_VALUE) { break; } int size = curr.size(); if (size >= 2 && num > curr.get(size - 1) + curr.get(size - 2)) { break; } if (size <= 1 || num == curr.get(size - 1) + curr.get(size - 2)) { curr.add((int)num); boolean found = splitIntoFibonacciHelper(i + 1, s, curr); if (found) { return true; } curr.remove(curr.size() - 1); } } return false; } }
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