feat: search-in-rotated-sorted-array

Author: minji-go

search-in-rotated-sorted-array/minji-go.java

@@ -0,0 +1,60 @@
+/**
+ * <a href="https://leetcode.com/problems/search-in-rotated-sorted-array/">week10-2. search-in-rotated-sorted-array</a>
+ * <li>Description: nums is sorted in ascending order and is possibly rotated at an unknown pivot index. return the index of target if it is in nums, or -1 </li>
+ * <li>Topics: Array, Binary Search </li>
+ * <li>Time Complexity: O(logN), Runtime 1ms      </li>
+ * <li>Space Complexity: O(logN), Memory 43.23MB </li>
+ */
+class Solution {
+    public int search(int[] nums, int target) {
+        if(nums.length==1) {
+            if(nums[0]==target) return 0;
+            return -1;
+        }
+
+        Queue<int[]> queue = new LinkedList<>();
+        queue.add(new int[]{0, nums.length-1});
+
+        int pivot = -1;
+        if(nums[0]<nums[nums.length-1]) {
+            pivot=nums.length-1;
+        }
+
+        while(pivot==-1 && !queue.isEmpty()){
+            int[] q = queue.poll();
+            int mid = (q[0]+q[1])/2;
+            if(mid+1 > nums.length-1) {
+                continue;
+            }
+            if(nums[mid]>nums[mid+1]) {
+                pivot=mid;
+                break;
+            }
+            queue.add(new int[]{q[0], mid});
+            queue.add(new int[]{mid+1, q[1]});
+        }
+
+        int left = 0, right = nums.length-1;
+        if(target>=nums[0] && target<=nums[pivot]) {
+            right = pivot;
+        } else {
+            left = pivot+1;
+        }
+
+
+        while(left<=right){
+            int mid = (left+right)/2;
+            if(target < nums[mid]) {
+                right=mid-1;
+            } else {
+                left=mid+1;
+            }
+        }
+
+        if(nums[right] == target) {
+            return right;
+        }
+
+        return -1;
+    }
+}