// version 1: find the first position >= target
public class Solution {
    public int searchInsert(int[] A, int target) {
        if (A == null || A.length == 0) {
            return 0;
        }
        int start = 0, end = A.length - 1;

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

        if (A[start] >= target) {
            return start;
        } else if (A[end] >= target) {
            return end;
        } else {
            return end + 1;
        }
    }
}

// version 2: find the last position < target, return +1， 要特判一下target小于所有数组里面的元素

public class Solution {
    public int searchInsert(int[] A, int target) {
        if (A == null || A.length == 0) {
            return 0;
        }
        int start = 0;
        int end = A.length - 1;
        int mid;

        if (target < A[0]) {
            return 0;
        }
        // find the last number less than target
        while (start + 1 < end) {
            mid = start + (end - start) / 2;
            if (A[mid] == target) {
                return mid;
            } else if (A[mid] < target) {
                start = mid;
            } else {
                end = mid;
            }
        }

        if (A[end] == target) {
            return end;
        }
        if (A[end] < target) {
            return end + 1;
        }
        if (A[start] == target) {
            return start;
        }
        return start + 1;
    }
}