# 300. Longest Increasing Subsequence

## 1. Question

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

A subsequence is a sequence that can be derived from an array by deleting some or no elements without changing the order of the remaining elements. For example, [3,6,2,7] is a subsequence of the array [0,3,1,6,2,2,7].

## 2. Examples

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


## 3. Constraints

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

## 5. Solutions

class Solution {
public int lengthOfLIS(int[] nums) {
int len = nums.length;
int max = 1;
if (len == 0) {
return 0;
}

int[] res = new int[len];
for (int i = 0; i < len; i++) {
res[i] = 1;
}

for (int i = 1; i < len; i++) {
for (int j = i - 1; j >= 0; j--) {
if (nums[i] > nums[j]) {
res[i] = Math.max(res[j] + 1, res[i]);
max = Math.max(res[i], max);
}
}
}
return max;
}
}