leetcode 300: Longest Increasing Subsequence

Longest Increasing Subsequence

Total Accepted: 53 Total Submissions: 172 Difficulty: Medium

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 is4. 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?

Credits:
Special thanks to @pbrother for adding this problem and creating all test cases.

[思路]

dp. d[i] 为 subset 0...i  的最大Longest increasing sub.

[code]

public class Solution {    public int lengthOfLIS(int[] nums) {        //[10, 2, 5, 3, 7],        if(nums==null || nums.length<1) return 0;                int [] d = new int[nums.length];        d[0] = 1;        int max = 1;        for(int i=1; i<nums.length; i++) {            d[i] = 1;            for(int j=0; j<i; j++) {                if(nums[i] > nums[j]) {                    d[i] = Math.max(d[i], d[j]+1);                }            }            max = Math.max(max, d[i]);        }        return max;    }}