Merge pull request #572 from wogha95/main

[재호] WEEK 12 Solutions

Author: SamTheKorean

merge-intervals/wogha95.js

@@ -0,0 +1,34 @@
+/**
+ * 정렬한 다음, 마지막 원소의 end값을 가지고 merge할지 원소 추가할지를 결정합니다.
+ *
+ * TC: O(N * logN)
+ * 정렬에 의해 N * logN 복잡도를 갖습니다.
+ *
+ * SC: O(1)
+ * 정답을 반환하는 공간을 제외하면 O(1), 포함하면 O(N)입니다.
+ *
+ * N: intervals.length
+ */
+
+/**
+ * @param {number[][]} intervals
+ * @return {number[][]}
+ */
+var merge = function (intervals) {
+  intervals.sort((a, b) => a[0] - b[0]);
+
+  return intervals.reduce((result, current) => {
+    if (result.length === 0) {
+      result.push(current);
+      return result;
+    }
+
+    const previous = result[result.length - 1];
+    if (previous[1] >= current[0]) {
+      result[result.length - 1][1] = Math.max(current[1], previous[1]);
+    } else {
+      result.push(current);
+    }
+    return result;
+  }, []);
+};

remove-nth-node-from-end-of-list/wogha95.js

@@ -0,0 +1,89 @@
+/**
+ * 2차
+ * n만큼 first가 움직인 다음, first가 끝까지 갈때까지 second를 움직입니다.
+ * 그럼 그 위치가 끝에서 n번째임을 알 수 있는 풀이입니다.
+ *
+ * TC: O(N)
+ * SC: O(1)
+ * N: list length
+ */
+
+/**
+ * Definition for singly-linked list.
+ * function ListNode(val, next) {
+ *     this.val = (val===undefined ? 0 : val)
+ *     this.next = (next===undefined ? null : next)
+ * }
+ */
+/**
+ * @param {ListNode} head
+ * @param {number} n
+ * @return {ListNode}
+ */
+var removeNthFromEnd = function (head, n) {
+  const resultHead = new ListNode(null, head);
+  let first = resultHead;
+  let second = resultHead;
+
+  while (n > 0) {
+    first = first.next;
+    n -= 1;
+  }
+
+  while (first.next) {
+    first = first.next;
+    second = second.next;
+  }
+
+  second.next = second.next.next;
+
+  return resultHead.next;
+};
+
+/**
+ * 1차
+ * 전체 순회로 갯수를 파악하고 해당 위치로가서 링크 연결 수정 작업
+ *
+ * TC: O(N)
+ * SC: O(1)
+ * N: list length
+ */
+
+/**
+ * Definition for singly-linked list.
+ * function ListNode(val, next) {
+ *     this.val = (val===undefined ? 0 : val)
+ *     this.next = (next===undefined ? null : next)
+ * }
+ */
+/**
+ * @param {ListNode} head
+ * @param {number} n
+ * @return {ListNode}
+ */
+var removeNthFromEnd = function (head, n) {
+  let listLength = 0;
+  let pointer = head;
+
+  while (pointer) {
+    pointer = pointer.next;
+    listLength += 1;
+  }
+
+  // if target of removal is the first node in list
+  if (listLength === n) {
+    return head.next;
+  }
+
+  let nextCount = listLength - n - 1;
+  pointer = head;
+
+  while (nextCount) {
+    pointer = pointer.next;
+    nextCount -= 1;
+  }
+
+  pointer.next = pointer.next.next;
+
+  return head;
+};

same-tree/wogha95.js

@@ -0,0 +1,48 @@
+/**
+ * TC: O(N)
+ * SC: O(N)
+ * N: count of node in tree
+ */
+
+/**
+ * Definition for a binary tree node.
+ * function TreeNode(val, left, right) {
+ *     this.val = (val===undefined ? 0 : val)
+ *     this.left = (left===undefined ? null : left)
+ *     this.right = (right===undefined ? null : right)
+ * }
+ */
+/**
+ * @param {TreeNode} p
+ * @param {TreeNode} q
+ * @return {boolean}
+ */
+var isSameTree = function (p, q) {
+  const queueP = [p];
+  const queueQ = [q];
+
+  while (queueP.length > 0 && queueQ.length > 0) {
+    const currentP = queueP.shift();
+    const currentQ = queueQ.shift();
+
+    if (currentP === null && currentQ === null) {
+      continue;
+    }
+
+    if (currentP === null || currentQ === null) {
+      return false;
+    }
+
+    if (currentP.val !== currentQ.val) {
+      return false;
+    }
+
+    queueP.push(currentP.left);
+    queueP.push(currentP.right);
+
+    queueQ.push(currentQ.left);
+    queueQ.push(currentQ.right);
+  }
+
+  return queueP.length === 0 && queueQ.length === 0;
+};