最长连续序列（算法）

public int findLongestConsequence(int [] A)
{
HashMap<Integer,Integer> map = new HashMap<Integer,Integer>();
int max = 1;
for(int i : A)
{
if(map.containKey(i) ) continue;
map.put(i,1);
if(map.containKey(i - 1))
max = Math.max(max,merge(map,i - 1,i);
if(map.containKey(i + 1))
max = Math.max(max,merge(map,i, i + 1));
}
return max;
}
private int merge(HashMap<Integer,Integer> map,int left,int right)
{
int upper = right + map.get(right) - 1;
int lower = left  - map.get(left) + 1;
int len = upper - lower + 1;
map.put(upper,len);
map.put(lower,len);
return len;
}