#HashSet查找复杂度为O(1)
#找最长连续序列只需要从不存在比自己-1的数字开始找即可
class Solution {
public int longestConsecutive(int[] nums) {
Set<Integer> set = new HashSet<>();
for(int num : nums){
set.add(num);
}
int LongestAns = 0;
for(Integer num : set){
if(!set.contains(num - 1)){
int CurrentNum = num;
int CurrentAns = 1;
while(set.contains(CurrentNum + 1)){
CurrentNum ++;
CurrentAns ++;
}
LongestAns = Math.max(LongestAns, CurrentAns);
}
}
return LongestAns;
}
}