[LintCode/LeetCode] Search Insert Position

Problem

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.

Example

[1,3,5,6], 5 → 2

[1,3,5,6], 2 → 1

[1,3,5,6], 7 → 4

[1,3,5,6], 0 → 0

Challenge

O(log(n)) time

Note

标准二分法题目。

Solution

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