[환미니니] Week9 Solutions

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

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

linked-list-cycle/hwanmini.js

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+// 시간복잡도: O(n)
+// 공간복잡도: O(1)
+
+/**
+ * Definition for singly-linked list.
+ * function ListNode(val) {
+ *     this.val = val;
+ *     this.next = null;
+ * }
+ */
+
+/**
+ * @param {ListNode} head
+ * @return {boolean}
+ */
+var hasCycle = function(head) {
+    let fastPointer = head;
+    let slowPointer = head;
+
+    while (fastPointer && fastPointer.next) {
+        slowPointer = slowPointer.next;
+        fastPointer = fastPointer.next.next
+
+        if (fastPointer === slowPointer) return true
+
+    }
+
+    return false
+};

maximum-subarray/hwanmini.js

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+// 시간복잡도: O(n)
+// 공간복잡도: O(1)
+
+/**
+ * @param {number[]} nums
+ * @return {number}
+ */
+var maxSubArray = function (nums) {
+    let maxNum = -Infinity;
+    let prevSum = -Infinity;
+
+    for (let i = 0 ; i < nums.length; i++) {
+        prevSum = Math.max(prevSum + nums[i], nums[i])
+        maxNum = Math.max(prevSum, maxNum)
+    }
+
+
+    return maxNum
+};