题解 | #二分查找#

import java.util.*;

public class BinarySearch {
    public int getPos(int[] A, int n, int val) {
        int left = 0, right = n-1;

        while (left < right) {
            int mid = (left + right) / 2;
            if (A[mid] >= val) {
                right = mid;
            } else {
                left = mid + 1;
            }
        }

        if (A[left] == val) {
            return left;
        } else {
            return -1;
        }
    }
}