SearchRange.cpp

/*
Search for a Range
Given a sorted array of integers, find the starting and ending position of a given target value. Your algorithm's runtime complexity must be in the order of O(log n). If the target is not found in the array, return [-1, -1]. Example: Given [5, 7, 7, 8, 8, 10] and target value 8, return [3, 4].
*/

int binarySearch(const vector<int>& A, int key, bool searchFirst){
    int start = 0;
    int end = A.size()-1;
    int mid;
    int result =  -1;
    while(start <= end){
        mid = start + (end-start)/2;
        if(A[mid] == key){
            result = mid;
            if(searchFirst){
                end = mid-1;
            }
            else{
                start = mid+1;
            }
        }
        else if(A[mid] > key){
            end = mid-1;
        }
        else{ // A[mid] < key
            start = mid+1;
        }
    }
    return result;
}

 
vector<int> Solution::searchRange(const vector<int> &A, int B) {
    // Do not write main() function.
    // Do not read input, instead use the arguments to the function.
    // Do not print the output, instead return values as specified
    // Still have a doubt. Checkout www.interviewbit.com/pages/sample_codes/ for more details
    vector<int> sol;
    
    sol.push_back(binarySearch(A, B, true));
    sol.push_back(binarySearch(A, B, false));
    
    return sol;
    
}