面試中的算法

• 給定一個數組a，長度爲n，求數組中所有兩個元素相加之和爲N的小標i和j

• import java.util.*;
  
  public class Main {
  
      public static void main(String[] args) {
          Scanner sc = new Scanner(System.in);
          int n = sc.nextInt();
          int N = sc.nextInt();
          int[] arr = new int[n];
          Map<Integer, Integer> map = new HashMap<>();
          for (int i=0;i<n;i++){
              arr[i] = sc.nextInt();
              map.put(arr[i],i);
          }
  
          for (int i=0;i<n;i++){
              int complement = N - arr[i];
              if (map.containsKey(complement)){
                  System.out.println(i+":"+map.get(complement));
              }
          }
      }
  }

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