[leetcode]最長の連続シーケンス-o（N）java

Longest Consecutive Sequence O Java

package leetCode import java.util.HashMap import java.util.Map /** * User: FR * Time: 1/4/15 6:01 PM * * Given an unsorted array of integers, find the length of the longest consecutive elements sequence. * For example, * Given [100, 4, 200, 1, 3, 2], * The longest consecutive elements sequence is [1, 2, 3, 4]. Return its length: 4. * Your algorithm should run in O(n) complexity. */ public class LongestConsecutiveSequence { public int longestConsecutive(int[] num) { int maxCounter=0 Map map = new HashMap() for(int n : num){ if(map.containsKey(n)) continue int[] array = new int[2] array[0]=n array[1]=n map.put(n, array) } for(int n : map.keySet()){ if(map.containsKey(n-1)){ map.get(n)[0] = map.get(n-1)[0] } if(map.containsKey(n+1)){ map.get(n)[1] = map.get(n+1)[1] } if((map.get(n)[1] - map.get(n)[0]+1)> maxCounter){ maxCounter = map.get(n)[1] - map.get(n)[0]+1 } map.get(map.get(n)[0])[1]=map.get(n)[1] map.get(map.get(n)[1])[0]=map.get(n)[0] } return maxCounter } public static void main(String[] args){ int[] a = {-3,2,8,5,1,7,-8,2,-8,-4,-1,6,-6,9,6,0,-7,4,5,-4,8,2,0,-2,-6,9,-4,-1} LongestConsecutiveSequence l = new LongestConsecutiveSequence() System.out.println(l.longestConsecutive(a)) } }