2024-01-05 Daily Challenge

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In: DailyChallenge
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Today I have done leetcode's January LeetCoding Challenge with cpp.

January LeetCoding Challenge 5

Description

Longest Increasing Subsequence

Given an integer array nums, return the length of the longest strictly increasing subsequence.

 

Example 1:

Input: nums = [10,9,2,5,3,7,101,18]
Output: 4
Explanation: The longest increasing subsequence is [2,3,7,101], therefore the length is 4.

Example 2:

Input: nums = [0,1,0,3,2,3]
Output: 4

Example 3:

Input: nums = [7,7,7,7,7,7,7]
Output: 1

 

Constraints:

  • 1 <= nums.length <= 2500
  • -104 <= nums[i] <= 104

 

Follow up: Can you come up with an algorithm that runs in O(n log(n)) time complexity?

Solution

auto speedup = [](){
  cin.tie(nullptr);
  cout.tie(nullptr);
  ios::sync_with_stdio(false);
  return 0;
}();
class Solution {
public:
  int lengthOfLIS(vector<int>& nums) {
    vector<int> LIS{nums[0]};
    for(auto i : nums) {
      auto it = lower_bound(LIS.begin(), LIS.end(), i);
      if(it != LIS.end()) {
        *it = i;
      } else {
        LIS.push_back(i);
      }
    }
    return LIS.size();
  }
};

// Accepted
// 55/55 cases passed (0 ms)
// Your runtime beats 100 % of cpp submissions
// Your memory usage beats 62.11 % of cpp submissions (10.8 MB)
Algorithm