[ganu] Week 10

invert-binary-tree/gwbaik9717.js

@@ -0,0 +1,33 @@
+// Time complexity: O(n)
+// Space complexity: 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) {
+  const dfs = (current) => {
+    if (!current) {
+      return;
+    }
+
+    const temp = current.left;
+    current.left = current.right;
+    current.right = temp;
+
+    dfs(current.left);
+    dfs(current.right);
+  };
+
+  dfs(root);
+
+  return root;
+};

jump-game/gwbaik9717.js

@@ -0,0 +1,28 @@
+// Time complexity: O(n)
+// Space complexity: O(1)
+
+/**
+ * @param {number[]} nums
+ * @return {boolean}
+ */
+var canJump = function (nums) {
+  let maxValue = nums[0];
+
+  for (let i = 1; i < nums.length; i++) {
+    if (i > maxValue) {
+      return false;
+    }
+
+    const newNum = i + nums[i];
+
+    if (newNum > maxValue) {
+      maxValue = newNum;
+    }
+
+    if (maxValue >= nums.length - 1) {
+      break;
+    }
+  }
+
+  return true;
+};

search-in-rotated-sorted-array/gwbaik9717.js

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+// Time complexity: O(logn)
+// Space complexity: O(1)
+
+/**
+ * @param {number[]} nums
+ * @param {number} target
+ * @return {number}
+ */
+var search = function (nums, target) {
+  let left = 0;
+  let right = nums.length - 1;
+
+  while (left <= right) {
+    const mid = Math.floor((left + right) / 2);
+
+    if (nums.at(mid) === target) {
+      return mid;
+    }
+
+    // rotate 된 구간이 있을 때
+    if (nums.at(mid + 1) > nums.at(right)) {
+      if (nums.at(right) >= target || nums.at(mid + 1) <= target) {
+        left = mid + 1;
+        continue;
+      }
+
+      right = mid - 1;
+      continue;
+    }
+
+    if (target >= nums.at(mid + 1) && target <= nums.at(right)) {
+      left = mid + 1;
+      continue;
+    }
+
+    right = mid - 1;
+  }
+
+  return -1;
+};