class Solution {
public:
    /**
     * @param A an integer array sorted in ascending order
     * @param target an integer
     * @return an integer
     */
    int closestNumber(vector<int>& A, int target) {
        // Write your code here


        int size = A.size();
        if (size == 0) {
            return -1;
        }

        int start = 0;
        int end = size - 1;

        while (start + 1 < end) {
            int mid = (end - start) / 2 + start;
            if (A[mid] == target) {
                return mid;
            } else if (A[mid] < target) {
                start = mid;
            } else {
                end = mid;
            }
        }

        if (target <= A[start]) {
            return start;
        }
        if (target >= A[end]) {
            return end;
        }
        // if A[start] < target < A[end], need to find which abs(difference) is smaller
        if (abs(target - A[start]) > abs(A[end] - target)) {
            return end;  
        } else {
            return start;
        }
        /*
        if (target > A[start] && target < A[end]) {
            if ((A[end] - target) >= (target - A[start])) {
                return start;
            } else {
                return end;
            }
        }
        */

    }
};