Press "Enter" to skip to content

Posts tagged as “parition”

花花酱 LeetCode 914. X of a Kind in a Deck of Cards

Problem

n a deck of cards, each card has an integer written on it.

Return true if and only if you can choose X >= 2 such that it is possible to split the entire deck into 1 or more groups of cards, where:

  • Each group has exactly X cards.
  • All the cards in each group have the same integer.

Example 1:

Input: [1,2,3,4,4,3,2,1]
Output: true
Explanation: Possible partition [1,1],[2,2],[3,3],[4,4]

Example 2:

Input: [1,1,1,2,2,2,3,3]
Output: false
Explanation: No possible partition.

Example 3:

Input: [1]
Output: false
Explanation: No possible partition.

Example 4:

Input: [1,1]
Output: true
Explanation: Possible partition [1,1]

Example 5:

Input: [1,1,2,2,2,2]
Output: true
Explanation: Possible partition [1,1],[2,2],[2,2]

Note:

  1. 1 <= deck.length <= 10000
  2. 0 <= deck[i] < 10000

Solution 1: HashTable + Brute Force

Try all possible Xs. 2 ~ deck.size()

Time complexity: ~O(n)

Space complexity: O(1)

C++

Solution 2: HashTable + GCD

Time complexity: O(nlogn)

Space complexity: O(1)

C++

Java

 

 

花花酱 LeetCode 842. Split Array into Fibonacci Sequence

Problem

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. 1 <= S.length <= 200
  2. S contains only digits.

Solution: DFS

Time complexity: O(2^n)

Space complexity: O(n)

C++