Details: http://codingdragon.tumblr.com/post/64975458402/find-a-key-in-circularly-shifted-sorted-array

FindSortedShifted.cpp

int find(vector<int> elements, int start, int end, int key){
    if(start>end) return -1;
    
    int mid = start + (end-start)/2;
    if(elements[mid]==key) return mid;
    
    if(elements[mid]>=elements[start]){
        if(key>=elements[start] && key<elements[mid]) return find(elements,start,mid-1,key);
        else return find(elements,mid+1,end,key);
    }else{
        if(key>elements[mid] && key<=elements[end]) return find(elements,mid+1,end,key);
        else return find(elements,start,mid-1,key);
    }
    
}