Question

package Easy;

import java.util.Arrays;
import java.util.HashMap;
import java.util.Map;


public class Demo1 {
    public static void main(String[] args) {
        int[] nums = {2, 7, 11, 15};
        int t = 26;
        int[] arr = twoSum(nums, t);
    System.out.println(Arrays.toString(arr));//printout is supposed to be [2,3],however it's [3, 4],what's wrong?
    }
    public static int[] twoSum(int[] numbers, int target) {
        int[] result = new int[2];  
        Map<Integer, Integer> map = new HashMap<Integer, Integer>();
        for (int i = 0; i < numbers.length; i++) {
            if (map.containsKey(target - numbers[i])) {
                result[1] = i + 1;
                result[0] = map.get(target - numbers[i]);
                return result;
            }
            map.put(numbers[i], i + 1);
        }
        return result;
    }
}

printout应该是[2,3]，不过它[3,4]，有什么不对吗？谢谢你的帮助。

描述：给定一个整数数组，返回两个数字的索引，使它们相加到特定目标。

You may assume that each input would have exactly one solution, and you may not use the same element twice.

Example:
Given nums = [2, 7, 11, 15], target = 9,

Because nums[0] + nums[1] = 2 + 7 = 9,
return [0, 1].

Answer 1

你的方式很复杂，你可以用更简单的方法解决它：

  int[] nums = {2, 7, 11, 15};
  ArrayList<Integer> index = new ArrayList<Integer>();
  int t = 26;
  for(int i=0 ; i < nums.length-1 ; i++){
      for(int j=i+1 ; j < nums.length ; j++){
          if(nums[i] + nums[j] == t){
               index.add(i);
               index.add(j);
          }
      }
  }
    System.out.println(index);

输出：

[2, 3]

检查：https://ideone.com/jM1wJQ

Java家务，一个简单的逻辑

1 个答案: