Closest Number in Sorted Array

题目描述

Given a target number and an integer array A sorted in ascending order, find the indexiin A such that A[i] is closest to the given target.

Return -1 if there is no element in the array.

Notice

There can be duplicate elements in the array, and we can return any of the indices with same value.

Example

Given[1, 2, 3]and target =2, return1.

Given[1, 4, 6]and target =3, return1.

Given[1, 4, 6]and target =5, return1or2.

Given[1, 3, 3, 4]and target =2, return0or1or2.

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代码

public class Solution {
    /**
     * @param A an integer array sorted in ascending order
     * @param target an integer
     * @return an integer
     */
    public int closestNumber(int[] A, int target) {
        // Write your code here
        if (A == null || A.length == 0) {
            return -1;
        }
        
        int start = 0;
        int end = A.length - 1;
        
        while (start + 1 < end) {
            int mid = start + (end - start) / 2;
            
            if(target== A[mid]) {
                return mid;
            } else if (target < A[mid]) {
                end = mid; 
            } else {
                start = mid;
            }
        }
        
        return (Math.abs(A[start] - target) < Math.abs(A[end] - target)) ? start : end;
        
    }
}