Merge pull request #76 from dev-jonghoonpark/main

[박종훈] 3주차 답안 제출

Author: DaleSeo

climbing-stairs/dev-jonghoonpark.md

@@ -0,0 +1,26 @@
+- https://leetcode.com/problems/climbing-stairs
+- time complexity : O(n)
+- space complexity : O(1)
+- https://algorithm.jonghoonpark.com/2024/02/09/leetcode-70
+
+```java
+class Solution {
+    public int climbStairs(int n) {
+        if (n == 1) {
+            return 1;
+        } else if (n == 2) {
+            return 2;
+        }
+
+        int result = 0;
+        int temp1 = 1, temp2 = 2;
+        for(int i = 3; i <= n; i++) {
+            result = temp1 + temp2;
+            temp1 = temp2;
+            temp2 = result;
+        }
+
+        return result;
+    }
+}
+```

maximum-depth-of-binary-tree/dev-jonghoonpark.md

@@ -0,0 +1,15 @@
+- https://leetcode.com/problems/maximum-depth-of-binary-tree
+- time complexity : O(n)
+- space complexity : O(n), 단 입력 트리가 balanced되어 있다면 O(logn)
+- https://algorithm.jonghoonpark.com/2024/02/18/leetcode-104
+
+```java
+class Solution {
+    public int maxDepth(TreeNode root) {
+        if (root == null) {
+            return 0;
+        }
+        return 1 + Math.max(maxDepth(root.left), maxDepth(root.right));
+    }
+}
+```

meeting-rooms/dev-jonghoonpark.md

@@ -0,0 +1,19 @@
+- https://leetcode.com/problems/meeting-rooms
+- https://neetcode.io/problems/meeting-schedule
+- time complexity : O(nlogn)
+- space complexity : O(n)
+- https://algorithm.jonghoonpark.com/2024/05/14/leetcode-252
+
+```java
+class Solution {
+    public boolean canAttendMeetings(List<Interval> intervals) {
+        intervals = intervals.stream().sorted(Comparator.comparingInt(o -> o.start)).toList();
+        for (int i = 0; i < intervals.size() - 1; i++) {
+            if(intervals.get(i).end > intervals.get(i+1).start) {
+                return false;
+            }
+        }
+        return true;
+    }
+}
+```

same-tree/dev-jonghoonpark.md

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+- https://leetcode.com/problems/same-tree
+- time complexity : O(n)
+- space complexity : O(n), 단 입력 트리가 balanced되어 있다면 O(logn)
+- https://algorithm.jonghoonpark.com/2024/03/31/leetcode-100
+
+```java
+public class Solution {
+    public boolean isSameTree(TreeNode p, TreeNode q) {
+        if (p == null && q == null) {
+            return true;
+        }
+
+        if (p == null || q == null) {
+            return false;
+        }
+
+        return p.val == q.val && isSameTree(p.left, q.left) && isSameTree(p.right, q.right);
+    }
+}
+```

subtree-of-another-tree/dev-jonghoonpark.md

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+- https://leetcode.com/problems/subtree-of-another-tree
+- root tree 의 노드 수를 n, sub tree 의 노드 수를 m 이라고 하였을 때
+  - time complexity : O(n \* m)
+  - space complexity : O(n + m), 단 입력 트리가 balanced되어 있다면 O(logn + logm)
+- https://algorithm.jonghoonpark.com/2024/05/14/leetcode-527
+
+```java
+public class Solution {
+    public boolean isSubtree(TreeNode root, TreeNode subRoot) {
+        if (root == null && subRoot == null) {
+            return true;
+        }
+
+        if (root == null || subRoot == null) {
+            return false;
+        }
+
+        if (isSubtreeStrict(root, subRoot)) {
+            return true;
+        }
+
+        return isSubtree(root.left, subRoot) || isSubtree(root.right, subRoot);
+    }
+
+    public boolean isSubtreeStrict(TreeNode root, TreeNode subRoot) {
+        if (root == null && subRoot == null) {
+            return true;
+        }
+
+        if (root == null || subRoot == null) {
+            return false;
+        }
+
+        return root.val == subRoot.val && isSubtreeStrict(root.left, subRoot.left) && isSubtreeStrict(root.right, subRoot.right);
+    }
+}
+```