[LeetCode]035. 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, note the last return: return left, which is the correct location if target is not in the array.

such a beautiful thinking!

Running Time: O(lgn).

public class Solution {
    public int searchInsert(int[] A, int target) {
        // Note: The Solution object is instantiated only once and is reused by each test case.
        int len = A.length;
        if(A==null || len==0){
            return -1;
        }
        int left = 0;
        int right = len - 1;
        while(left<=right){
            int mid = (left+right)/2;
            if(A[mid] == target){
                return mid;
            }else if(A[mid] > target){
                right = mid - 1;
            }else{
                left = mid + 1;
            }
        }
        return left;
        //if the targer is not in the array, the left is the correct location
        //cool!
    }
}