Search in Rotated Sorted Array

Search in Rotated Sorted Array.cpp

@@ -0,0 +1,45 @@
+class Solution {
+public:
+    int prevElement(vector<int>& nums){
+        int n=nums.size();
+        int start=0;
+        int end=n-1;
+        if(nums[0]<nums[n-1])
+            return nums[0];
+        while(start<=end){
+            int mid=start+(end-start)/2;
+            int next=(mid+1)%n;
+            int prev=(mid+n-1)%n;
+            if(nums[mid]<=nums[next] && nums[mid]<=nums[prev])
+                return mid;
+            if(nums[0]<=nums[mid])
+                start=mid+1;
+            else if(nums[n-1]>=nums[mid])
+                end=mid-1;
+        }
+        return -1;
+    }
+    int bSearch(vector<int>& nums, int start, int end, int target){
+        while(start<=end){
+            int mid=start+(end-start)/2;
+            if(target == nums[mid])
+                return mid;
+            else if(target < nums[mid])
+                end=mid-1;
+            else
+                start=mid+1;
+        }
+        return -1;
+    }
+    int search(vector<int>& nums, int target) {
+        int index = prevElement(nums);
+        int first = bSearch(nums, 0, index-1, target);
+        int second =bSearch(nums, index, nums.size()-1, target);
+        if(first>=0 && second==-1)
+            return first;
+        else if(first == -1 && second>=0)
+            return second;
+        else
+            return -1;
+    }
+};