33. Search in Rotated Sorted Array / Medium / JavaScript

yeongrok/0033-search-in-rotated-sorted-array/0033-search-in-rotated-sorted-array.js

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+/**
+ * @param {number[]} nums
+ * @param {number} target
+ * @return {number}
+ */
+var search = function(nums, target) {
+    if (nums.length === 1) return nums[0] === target ? 0 : -1;
+
+    // 정렬
+    let start = 0;
+    if (nums[0] > nums[nums.length - 1]) {
+        while (nums[start] < nums[start+1]) start++;
+        start++;
+        nums = [...nums.slice(start), ...nums.slice(0, start)];
+    }
+
+    // 절반씩 잘라가며 찾기
+    var _search = (arr, startIndexOfOrigin) => {
+        const { length: l } = arr;
+        if (l === 0) return -1;
+        if (l === 1) return arr[0] === target ? startIndexOfOrigin : -1;
+
+        const m = Math.floor(l / 2);
+        if (arr[m] < target) {
+            return _search(arr.slice(m + 1), startIndexOfOrigin + m + 1);
+        } else if (arr[m] === target) {
+            return startIndexOfOrigin + m;
+        } else {
+            return _search(arr.slice(0, m), startIndexOfOrigin);
+        }
+    }
+
+    const v = _search(nums, 0);
+    return v === -1 ? -1 : start === 0 ? v : (v + start) % nums.length;
+};

yeongrok/0033-search-in-rotated-sorted-array/README.md

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+<h2><a href="https://leetcode.com/problems/search-in-rotated-sorted-array/">33. Search in Rotated Sorted Array</a></h2><h3>Medium</h3><hr>Can you solve this real interview question? Search in Rotated Sorted Array - There is an integer array nums sorted in ascending order (with distinct values).
+
+Prior to being passed to your function, nums is possibly rotated at an unknown pivot index k (1 <= k < nums.length) such that the resulting array is [nums[k], nums[k+1], ..., nums[n-1], nums[0], nums[1], ..., nums[k-1]] (0-indexed). For example, [0,1,2,4,5,6,7] might be rotated at pivot index 3 and become [4,5,6,7,0,1,2].
+
+Given the array nums after the possible rotation and an integer target, return the index of target if it is in nums, or -1 if it is not in nums.
+
+You must write an algorithm with O(log n) runtime complexity.
+
+
+
+Example 1:
+
+Input: nums = [4,5,6,7,0,1,2], target = 0
+Output: 4
+
+
+Example 2:
+
+Input: nums = [4,5,6,7,0,1,2], target = 3
+Output: -1
+
+
+Example 3:
+
+Input: nums = [1], target = 0
+Output: -1
+
+
+
+
+Constraints:
+
+ * 1 <= nums.length <= 5000
+ * -104 <= nums[i] <= 104
+ * All values of nums are unique.
+ * nums is an ascending array that is possibly rotated.
+ * -104 <= target <= 104