1414. Find the Minimum Number of Fibonacci Numbers Whose Sum Is K

1414. Find the Minimum Number of Fibonacci Numbers Whose Sum Is K

Difficulty: Medium

Related Topics: Array, Greedy

Given the number k, return the minimum number of Fibonacci numbers whose sum is equal to k, whether a Fibonacci number could be used multiple times.

The Fibonacci numbers are defined as:

  • F1 = 1
  • F2 = 1
  • Fn = Fn-1 + Fn-2 , for n > 2.

It is guaranteed that for the given constraints we can always find such fibonacci numbers that sum k.

Example 1:

Input: k = 7
Output: 2 
Explanation: The Fibonacci numbers are: 1, 1, 2, 3, 5, 8, 13, ... 
For k = 7 we can use 2 + 5 = 7.

Example 2:

Input: k = 10
Output: 2 
Explanation: For k = 10 we can use 2 + 8 = 10.

Example 3:

Input: k = 19
Output: 3 
Explanation: For k = 19 we can use 1 + 5 + 13 = 19.

Constraints:

  • 1 <= k <= 10^9

Solution

Language: Python3

class Solution:
    def findMinFibonacciNumbers(self, k: int) -> int:
        cur=[1,1]
        while cur[-1]+cur[-2]<=k:
            cur.append(cur[-1]+cur[-2])
        
        rep=0
        while k>0:
            k-=cur[-1]
            rep+=1
            while k>0 and cur[-1]>k:
                cur.pop()
        return rep

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