[환미니니] Week10 Solutions

invert-binary-tree/hwanmini.js

@@ -0,0 +1,30 @@
+// 시간복잡도: O(n)
+// 공간복잡도: O(n)
+
+/**
+ * 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} root
+ * @return {TreeNode}
+ */
+var invertTree = function(root) {
+    if (!root) return null;
+
+    const left = root.left
+    const right = root.right
+
+    root.left = right
+    root.right = left
+
+
+    invertTree(left)
+    invertTree(right)
+
+    return root
+};

jump-game/hwanmini.js

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+// 시간복잡도: O(n)
+// 공간복잡도: O(1)
+
+/**
+ * @param {number[]} nums
+ * @return {boolean}
+ */
+var canJump = function(nums) {
+    let fast = 0;
+
+    for (let i = 0; i < nums.length; i++) {
+        if (i > 0 && i > fast) return false
+
+        fast = Math.max(fast, i + nums[i])
+
+        if (fast >= nums.length -1) return true
+    }
+
+    return false
+};

search-in-rotated-sorted-array/hwanmini.js

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+// 시간복잡도: O(log n)
+// 공간복잡도: O(1)
+
+/**
+ * @param {number[]} nums
+ * @param {number} target
+ * @return {number}
+ */
+var search = function(nums, target) {
+    let leftIdx = 0;
+    let rightIdx = nums.length - 1;
+
+    while (leftIdx <= rightIdx) {
+        const midIdx = Math.floor((leftIdx + rightIdx) / 2);
+
+        if (nums[midIdx] === target) return midIdx;
+
+        if (nums[leftIdx] <= nums[midIdx]) {
+            if (nums[leftIdx] <= target && nums[midIdx] >= target) {
+                rightIdx = midIdx - 1;
+            } else {
+                leftIdx = midIdx + 1;
+            }
+        } else {
+            if (nums[rightIdx] >= target && nums[midIdx] <= target) {
+                leftIdx = midIdx + 1;
+            } else {
+                rightIdx = midIdx - 1;
+            }
+        }
+    }
+
+    return -1
+};