feat: solve longest increasing subsequence

Author: GangBean

longest-increasing-subsequence/GangBean.java

@@ -0,0 +1,22 @@
+class Solution {
+    /**
+    1. understanding
+    - dp[n] : length of longest increasing subsequence in 0...n
+    2. space
+    - time: O(N^2)
+    - space: O(N)
+     */
+    public int lengthOfLIS(int[] nums) {
+        int[] dp = new int[nums.length];
+        Arrays.fill(dp, 1);
+        for (int i = 0; i < nums.length; i++) { // O(N)
+            for (int j = 0; j <= i; j++) { // O(N)
+                if (nums[j] < nums[i]) {
+                    dp[i] = Math.max(dp[j]+1, dp[i]);
+                }
+            }
+        }
+        return Arrays.stream(dp).max().orElse(1);
+    }
+}
+