[Yiseull] WEEK 10 Solutions

invert-binary-tree/Yiseull.java

@@ -0,0 +1,22 @@
+/**
+ * Definition for a binary tree node.
+ * public class TreeNode {
+ *     int val;
+ *     TreeNode left;
+ *     TreeNode right;
+ *     TreeNode() {}
+ *     TreeNode(int val) { this.val = val; }
+ *     TreeNode(int val, TreeNode left, TreeNode right) {
+ *         this.val = val;
+ *         this.left = left;
+ *         this.right = right;
+ *     }
+ * }
+ */
+class Solution {
+    public TreeNode invertTree(TreeNode root) {
+        if (root == null) return null;
+
+        return new TreeNode(root.val, invertTree(root.right), invertTree(root.left));
+    }
+}

search-in-rotated-sorted-array/Yiseull.java

@@ -0,0 +1,28 @@
+class Solution {
+    // 공간복잡도: O(1), 시간복잡도: O(logn)
+    public int search(int[] nums, int target) {
+        int left = 0, right = nums.length - 1;
+
+        while (left < right) {
+            int mid = (left + right) / 2;
+
+            // 오른쪽 정렬
+            if (nums[mid] < nums[right]) {
+                if (nums[mid] <= target && target <= nums[right]) {
+                    if (nums[mid] == target) return mid;
+                    left = mid + 1;
+                }
+                else right = mid - 1;
+            // 왼쪽 정렬
+            } else {
+                if (nums[left] <= target && target <= nums[mid]) {
+                    if (nums[mid] == target) return mid;
+                    right = mid - 1;
+                }
+                else left = mid + 1;
+            }
+        }
+
+        return nums[left] == target ? left : -1;
+    }
+}