Search Insert Position

Given a sorted array and a target value, return the index if the target is found. If not, return the index where it would be if it were inserted in order.

You may assume no duplicates in the array.

Here are few examples.

[1,3,5,6], 5 → 2
[1,3,5,6], 2 → 1
[1,3,5,6], 7 → 4
[1,3,5,6], 0 → 0

Solution

Binary search.

Complexity

时间复杂度 O(logn)，空间复杂度 O(1)

Code

public class Solution {
    public int searchInsert(int[] A, int target) {
        int i = 0, j = A.length - 1;
        while (i <= j) {
            int mid = (i + j) / 2;
            if (A[mid] == target) return mid;
            if (A[mid] < target) i = mid + 1;
            else j = mid - 1;
        }
        return i;
    }
}