Longest Increasing Subsequence

class Solution {
public:
    int lengthOfLIS(vector<int>& nums) {
        int n=nums.size();
        vector<int> lis;
        for(int i=0;i<n;++i){
            int lb = lower_bound(lis.begin(),lis.end(),nums[i])-lis.begin();
            if(lb==lis.size())
                lis.push_back(nums[i]);
            else
                lis[lb] = nums[i];
        }
        return lis.size();
    }
};