4. Longest Increasing Subsequence

Author: Sunjae95

longest-increasing-subsequence/sunjae95.js

@@ -0,0 +1,35 @@
+/**
+ * @description
+ * brainstorming:
+ * 1. dfs -> time limited
+ * 2. memoization + dfs
+ *
+ * n: length of nums
+ * time complexity: O(n^2)
+ * space complexity: O(n)
+ */
+var lengthOfLIS = function (nums) {
+  const memo = new Array(nums.length).fill(-1);
+  let answer = 0;
+
+  const dfs = (index) => {
+    if (memo[index] !== -1) return memo[index];
+
+    let maxLength = 1;
+
+    for (let i = index + 1; i < nums.length; i++) {
+      if (nums[index] < nums[i]) {
+        maxLength = Math.max(maxLength, 1 + dfs(i));
+      }
+    }
+
+    memo[index] = maxLength;
+    return maxLength;
+  };
+
+  for (let i = 0; i < nums.length; i++) {
+    answer = Math.max(answer, dfs(i));
+  }
+
+  return answer;
+};