README_EN.md

300. Longest Increasing Subsequence

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Description

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

Example:

Input: [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. 

Note:

• 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?

Solutions

Python3

class Solution:
    def lengthOfLIS(self, nums: List[int]) -> int:
        n = len(nums)
        if n < 2:
            return n
        dp = [1] * n
        res = 1
        for i in range(1, n):
            for j in range(i):
                if nums[j] < nums[i]:
                    dp[i] = max(dp[i], dp[j] + 1)
            res = max(res, dp[i])
        return res

Java

class Solution {
    public int lengthOfLIS(int[] nums) {
        int n = nums.length;
        int[] dp = new int[n];
        Arrays.fill(dp, 1);
        int res = 1;
        for (int i = 1; i < n; ++i) {
            for (int j = 0; j < i; ++j) {
                if (nums[j] < nums[i]) {
                    dp[i] = Math.max(dp[i], dp[j] + 1);
                }
            }
            res = Math.max(res, dp[i]);
        }
        return res;
    }
}

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