l 4000 eetcode-1 Two Sum 找到数组中两数字和为指定和

问题描述：在一个数组（无序）中快速找出两个数字，使得两个数字之和等于一个给定的值。假设数组中肯定存在至少一组满足要求。

public class test1 {

    public static int[] twoSum(int[] nums, int target) {

        for (int i = 0; i < nums.length; i++) {
for (int j = i + 1; j < nums.length; j++) {
if (nums[i] + nums[j] == target) {
return new int[]{i,j};
}
}
}
return new int[]{-1};//return -1 if target isn't exist;

    }

     public static void main(String[] args) {
int[] arr = {2, 7, 11, 15};
int target = 17;
int[] res = twoSum(arr, target);
for (int i = 0; i < res.length; i++) {
System.out.println(res[i]);//0,1
}
}

}