add: 491. Non-decreasing Subsequences

Author: Junhyeong-B

LeetCode/Medium/491. Non-decreasing Subsequences.ts

@@ -0,0 +1,37 @@
+/**
+ * Runtime 8118 ms Beats 5.55%
+ * Memory 62.2 MB Beats 52.78%
+ */
+
+function findSubsequences(nums: number[]): number[][] {
+  const answer: number[][] = [];
+  const set = new Set<string>();
+  const dfs = (index: number, temp: number[]) => {
+    if (index === nums.length) {
+      if (temp.length <= 1) {
+        return;
+      }
+      const key = temp.join('/');
+      if (set.has(key)) {
+        return;
+      }
+
+      answer.push([...temp]);
+      set.add(key);
+    } else {
+      const lastNumber = temp[temp.length - 1] ?? -101;
+      for (let i = index; i < nums.length; i++) {
+        dfs(i + 1, temp);
+        if (lastNumber <= nums[i]) {
+          dfs(i + 1, [...temp, nums[i]]);
+        }
+      }
+    }
+  };
+
+  dfs(0, []);
+
+  return answer;
+}
+
+console.log(findSubsequences([4, 6, 7, 7])); // [[7, 7], [6, 7], [6, 7, 7], [4, 7], [4, 7, 7], [4, 6], [4, 6, 7], [4, 6, 7, 7]]