Leetcode001 -- returns the subscript of the array element whose sum is target

import java.sql.SQLOutput;
import java.util.HashMap;
import java.util.Map;
import java.util.Scanner;

public class test01 {
    /**
     *  Given an array of integers  nums And an integer target value  target, Please find... In the array   And is the target value  target  The two integers of , And return their array subscripts .
     *  You can assume that each input corresponds to only one answer . however , The same element in the array cannot be repeated in the answer .
     *  You can return the answers in any order .
     *
     *  Example  1：
     *  Input ：nums = [2,7,11,15], target = 9
     *  Output ：[0,1]
     *  explain ： because  nums[0] + nums[1] == 9 , return  [0, 1] .
     *
     *  Example  2：
     *  Input ：nums = [3,2,4], target = 6
     *  Output ：[1,2]
     *
     *  Example  3：
     *  Input ：nums = [3,3], target = 6
     *  Output ：[0,1]
     *
     *  Tips ：
     * 2 <= nums.length <= 104
     * -109 <= nums[i] <= 109
     * -109 <= target <= 109
     *  There will only be one valid answer 
     * @param args
     */


    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        System.out.println(" Please enter the size of the array ：");
        int size = sc.nextInt();
        System.out.println(" Please enter "+size+" Number ：");
        int[] nums = new int[size];
        for( int i = 0; i < size; i++){
            nums[i] = sc.nextInt();
        }

        System.out.println(" Please enter the target value ：");
        int target = sc.nextInt();

        int[] result = twoSumHashmap(nums,target);



        StringBuilder sb = new StringBuilder();
        sb.append("[");
        for (int i=0; i< result.length-1; i++){
            sb.append(result[i]);
            sb.append(",");
        }
        sb.append(result[result.length-1]);
        sb.append("]");
        System.out.println(sb);


    }

    public static int[] twoSum(int[] nums, int target){
        int length = nums.length;
        int[] result = new int[2];
        for(int i=0; i<length-1; i++){
            for (int j=i+1; j<length; j++){
                if( nums[i] + nums[j] == target ){
                    result[0] = i;
                    result[1] = j;
                    return result;
                }
            }
        }
        return new int[0];
    }


    /**
     *  use static The method of decoration , This method can be called without generating an instance object of the class .
     *  No, static The method of decoration , You need to generate an instance object of a class before you can call this method .
     * @param nums
     * @param target
     * @return
     */
    public static int[] twoSumHashmap(int[] nums, int target){
        Map<Integer, Integer> map = new HashMap<Integer, Integer>();
        for( int i=0; i<nums.length; i++){
            if(map.containsKey(target-nums[i])){
                map.put(nums[i],i);
                return new int[]{map.get(target-nums[i]),i};
            }
            map.put(nums[i],i);
        }
        return new int[0];
    }

}