求两数之和（三种解法）

给定一个升序排列的整数数组numbers ，从数组中找出两个数满足相加之和等于目标数 target。

假设每个输入只对应唯一的答案，而且不可以重复使用相同的元素。

返回两数的下标值，以数组形式返回

import java.lang.reflect.Array;
import java.util.Arrays;

public class searchTarget {
    public static void main(String[] args) {
        System.out.println(Arrays.toString(twoSearch(new int[]{1,4,6,7,8,20,21},7)));
        System.out.println(Arrays.toString(bf(new int[]{1,4,6,7,8,20,21},7)));
        System.out.println(Arrays.toString(twoPoin(new int[]{1,4,6,7,8,20,21},7)));
    }

    //暴力算法
    public static int[] bf(int[] numbers,int target){
        for (int i = 0; i <numbers.length ; i++) {
            int low =i, hight = numbers.length-1;
            for (int j = i+1; j <numbers.length ; j++) {
                if (numbers[i] + numbers[j] == target){
                    return new int[]{i,j};
                }
            }
        }
        return null;
    }

    //二分查找数组中两个数是否大于target
    public static int[] twoSearch(int[] numbers,int target){
        for (int i = 0; i < numbers.length; i++) {
            int low =i, hight = numbers.length-1;
            while(low <= hight){
                int mid = low + (hight - low)/2;
                if (numbers[i] == target - numbers[mid]){
                    return new int[]{i,mid};
                }else if(numbers[i] > target - numbers[mid]){
                    hight = mid -1;
                }else{
                    low = mid +1;
                }
            }
        }
        return new int[]{0};
    }

    //双指针算法
    public static int[] twoPoin(int[] numbers,int target){
            int low = 0, hight = numbers.length-1;
            while(low<hight){
                if (numbers[low] + numbers[hight] == target){
                    return new int[]{low,hight};
                }else if (numbers[low] + numbers[hight] > target){
                    hight --;
                }else if (numbers[low] + numbers[hight] < target){
                    low --;
                }
            }
            return null;
    }
}