[reeseo3o] WEEK 07 Solutions

reverse-linked-list/reeseo3o.js

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+// Time Complexity: O(n) - 노드를 한 번만 순회
+// Space Complexity: O(1) - 변수 3개(prev, current, next)만 사용
+const reverseList = (head) => {
+    let prev = null;
+    let current = head;
+
+    while (current !== null) {
+        const next = current.next;
+        current.next = prev;
+        prev = current;
+        current = next;
+    }
+
+    return prev;
+};
+
+// Time Complexity: O(n) - 노드 수만큼 재귀 호출
+// Space Complexity: O(n) - 콜 스택이 노드 수만큼 쌓임
+const reverseListRecursive = (head) => {
+    if (head === null || head.next === null) return head;
+
+    const newHead = reverseListRecursive(head.next);
+
+    head.next.next = head;
+    head.next = null;     
+
+    return newHead;
+};