[ganu] Week9

find-minimum-in-rotated-sorted-array/gwbaik9717.js

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+// Time complexity: O(logn)
+// Space complexity: O(1)
+
+/**
+ * @param {number[]} nums
+ * @return {number}
+ */
+var findMin = function (nums) {
+  let left = 0;
+  let right = nums.length - 1;
+
+  while (left < right) {
+    const mid = Math.floor((left + right) / 2);
+
+    if (nums.at(mid - 1) > nums.at(mid)) {
+      return nums[mid];
+    }
+
+    if (nums.at(mid + 1) < nums.at(mid)) {
+      return nums[mid + 1];
+    }
+
+    if (nums.at(mid + 1) > nums.at(right)) {
+      left = mid + 1;
+      continue;
+    }
+
+    right = mid - 1;
+  }
+
+  return nums[left];
+};

linked-list-cycle/gwbaik9717.js

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+// Time complexity: O(n)
+// Space complexity: O(1)
+
+/**
+ * @param {ListNode} head
+ * @return {boolean}
+ */
+var hasCycle = function (head) {
+  let turtle = head;
+  let rabbit = head;
+
+  while (turtle && rabbit && rabbit.next) {
+    turtle = turtle.next;
+    rabbit = rabbit.next.next;
+
+    if (turtle === rabbit) {
+      return true;
+    }
+  }
+
+  return false;
+};

maximum-product-subarray/gwbaik9717.js

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+// Time complexity: O(n)
+// Space complexity: O(n)
+
+/**
+ * @param {number[]} nums
+ * @return {number}
+ */
+var maxProduct = function (nums) {
+  let answer = nums[0];
+  const products = Array.from({ length: nums.length + 1 }, () => null);
+  products[0] = [1, 1]; // [min, max]
+
+  for (let i = 1; i < products.length; i++) {
+    const cases = [];
+
+    // case 1
+    cases.push(nums[i - 1]);
+
+    // case 2
+    cases.push(nums[i - 1] * products[i - 1][0]);
+
+    // case 3
+    cases.push(nums[i - 1] * products[i - 1][1]);
+
+    const product = [Math.min(...cases), Math.max(...cases)];
+    products[i] = product;
+    answer = Math.max(answer, product[1]);
+  }
+
+  return answer;
+};