[선재] WEEK 12 Solution

merge-intervals/sunjae95.js

@@ -0,0 +1,28 @@
+/**
+ * @description
+ * 각 intervals의 시작점을 기준으로 정렬 후 tmp의 end와 각 start를 비교하여 풀이
+ *
+ * n = length of intervals
+ * time complexity: O(n log n)
+ * space complexity: O(n)
+ */
+var merge = function (intervals) {
+  intervals.sort((a, b) => a[0] - b[0]);
+
+  const answer = [];
+  let mergeTmp = intervals[0];
+
+  for (let i = 1; i < intervals.length; i++) {
+    const [start, end] = intervals[i];
+
+    if (mergeTmp[1] >= start) mergeTmp[1] = Math.max(mergeTmp[1], end);
+    else {
+      answer.push(mergeTmp);
+      mergeTmp = [start, end];
+    }
+  }
+
+  answer.push(mergeTmp);
+
+  return answer;
+};

remove-nth-node-from-end-of-list/sunjae.js

@@ -0,0 +1,36 @@
+/**
+ * @description
+ * 전체 노드의 길이를 구한 뒤 n에 적합한 노드만 건너뛰어 노드를 재배열 시켜줌
+ *
+ * n = total length of head node list
+ * time complexity: O(n)
+ * space complexity: O(n)
+ */
+var removeNthFromEnd = function (head, n) {
+  let node;
+  let nodeCount = 0;
+
+  node = head;
+  while (node) {
+    nodeCount++;
+    node = node.next;
+  }
+
+  let answer = new ListNode();
+  let answerNode = answer;
+
+  node = head;
+  for (let i = 0; i < nodeCount; i++) {
+    if (nodeCount - n === i) {
+      i++;
+      node = node.next;
+    }
+
+    answerNode.next = node;
+    answerNode = node;
+
+    node = node?.next ?? null;
+  }
+
+  return answer.next;
+};

same-tree/sunjae95.js

@@ -0,0 +1,22 @@
+/**
+ * @description
+ * 두개의 트리를 동시에 순회한다를 초점으로 문제접근하여 풀이
+ *
+ * n = minimum tree node count of p or q
+ * time complexity: O(n)
+ * space complexity: O(1)
+ */
+var isSameTree = function (p, q) {
+  const preOrder = (tree1, tree2) => {
+    if (!tree1 && !tree2) return true;
+    if (!tree1 || !tree2) return false;
+
+    if (tree1.val !== tree2.val) return false;
+    if (!preOrder(tree1.left, tree2.left)) return false;
+    if (!preOrder(tree1.right, tree2.right)) return false;
+
+    return true;
+  };
+
+  return preOrder(p, q);
+};