LeetCode [846] Hand of Straights

 846. Hand of Straights

Medium

Alice has a hand of cards, given as an array of integers.

Now she wants to rearrange the cards into groups so that each group is size W, and consists of W consecutive cards.

Return true if and only if she can.

 

Example 1:

Input: hand = [1,2,3,6,2,3,4,7,8], W = 3
Output: true
Explanation: Alice's hand can be rearranged as [1,2,3],[2,3,4],[6,7,8].

Example 2:

Input: hand = [1,2,3,4,5], W = 4
Output: false
Explanation: Alice's hand can't be rearranged into groups of 4.

 

Constraints:

• 1 <= hand.length <= 10000
• 0 <= hand[i] <= 10^9
• 1 <= W <= hand.length

Note: This question is the same as 1296: https://leetcode.com/problems/divide-array-in-sets-of-k-consecutive-numbers/

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class Solution { public boolean isNStraightHand(int[] hand, int W) { Map<Integer, Integer> count = new TreeMap<>(); for(int i : hand) count.put(i, count.getOrDefault(i, 0)+1); for(int k : count.keySet()){ if(count.get(k)==0) continue; int last = k + W-1; for(int j=last; j>=k; --j){ if(count.getOrDefault(j, 0) < count.get(k)) return false; count.put(j, count.get(j)-count.get(k)); } } return true; } }