leecode_300 Longest Increasing Subsequence

Given an unsorted array of integers, find the length of longest increasing subsequence.

For example,

Given 

[10, 9, 2, 5, 3, 7, 101, 18]

,

The longest increasing subsequence is 

[2, 3, 7, 101]

, therefore the length is 

4

.
Note that there may be more than one LIS combination, it is only necessary for you to return the length.

Your algorithm should run in O(n2) complexity.

Follow up: Could you improve it to O(n log n) time complexity?

c++的写过了，来一发java版的实现：

public class Solution {
public int lengthOfLIS(int[] nums) {

TreeSet<Integer> ts= new TreeSet<Integer>();

for (int i=0;i<nums.length;i++)
ts.add(Integer.MIN_VALUE);

int len=0;

for (int i=0;i<nums.length;i++){
Integer ee=ts.ceiling(nums[i]);
if (ee!=null){
ts.remove(ee);
ts.add(nums[i]);
}
else{
ts.add(nums[i]);
len++;
}

}

return len;
}
}