search-in-rotated-sorted-array solution

Author: jdy8739

search-in-rotated-sorted-array/jdy8739.js

@@ -0,0 +1,67 @@
+/**
+ * @param {number[]} nums
+ * @param {number} target
+ * @return {number}
+ */
+var search = function (nums, target) {
+    const pivotIndex = findPivot(nums);
+
+    const firstHalfResult = findIndex(nums, 0, pivotIndex - 1, target);
+
+    return firstHalfResult === -1 ? findIndex(nums, pivotIndex, nums.length - 1, target) : firstHalfResult;
+};
+
+function findIndex(nums, start, end, target) {
+    while (start <= end) {
+        // console.log(start, end, target)
+        const mid = start + Math.floor((end - start) / 2);
+
+        const midValue = nums[mid];
+
+        if (midValue === target) {
+            return mid;
+        }
+
+        if (nums[start] === target) {
+            return start;
+        }
+
+        if (nums[end] === target) {
+            return end;
+        }
+
+        if (nums[mid] < target) {
+            start = mid + 1;
+        } else if (nums[mid] > target) {
+            end = mid - 1;
+        }
+    }
+
+    return -1;
+}
+
+
+function findPivot(nums) {
+    let low = 0;
+    let high = nums.length - 1;
+
+    while (low <= high) {
+        const mid = low + Math.floor((high - low) / 2);
+
+        if (0 < mid && nums[mid - 1] > nums[mid]) {
+            return mid;
+        }
+
+        if (nums[0] <= nums[mid]) {
+            low = mid + 1;
+        } else {
+            high = mid - 1;
+        }
+
+    }
+
+    return 0;
+}
+
+// 시간복잡도 O(logn) -> 피봇, 최소값을 찾을 때 이진탐색을 사용하므로
+// 공간복잡도 O(1) -> 고정된 변수 사용 이외에는 동적인 배열, 객체를 사용하지 않으므로