[Hackerrank] ice cream parlor

Sunny and Johnny together have M dollars which they intend to use at the ice cream parlour. among n flavors available, they have to choose two distinct flavors whose cost equals m. given a list of cost of N flavors, output the indices of two items whose sum equals m. the cost of a flavor (CI) will be no more than 10000.

Input Format

The first line of the input contains t, t test cases follow.
Each test case follows the format: the first line contains M. The second line contains the number n. The third line contains n single space separated integers denoting the price of each flavor CI.

Output Format

Output two integers, each of which is a valid index of the flavor. The lower index must be printed first. Indices are indexed from 1 to n.

Constraints

1 ≤ T ≤ 50
2 ≤ m ≤ 10000
2 ≤ n ≤ 10000
1 ≤ CI ≤10000
The prices of two items may be same and each test case has a unique solution.

 

It is also a problem of finding two numbers in the array and M, similar to the two sum problem in leetcode.

In this case, the number in the array may be repeated, so the value in the map should be saved as an arraylist.

In addition, make sure that I is smaller than the coordinates found in map (as shown in the judgment of 26 lines of code) to avoid duplication.

The Code is as follows:

 1 import java.util.*; 2  3 public class Solution { 4     public static void main(String[] args) { 5         Scanner in = new Scanner(System.in); 6         int t = in.nextInt(); 7         while(t-- >0){ 8             int m = in.nextInt(); 9             int n = in.nextInt();10             int[] prices = new int[n];11             HashMap<Integer, ArrayList<Integer>> map = new HashMap<Integer, ArrayList<Integer>>();12             13             for(int i = 0;i < n;i++){14                 prices[i]=in.nextInt();15                 if(!map.containsKey(prices[i]))16                     map.put(prices[i], new ArrayList<Integer>());17                 map.get(prices[i]).add(i);18             }19             20             for(int i = 0;i < n;i++){21                 int has = prices[i];22                 int toFind = m-prices[i];23                 24                 if(map.containsKey(toFind)){25                     for(int temp:map.get(toFind)){26                         if(i < temp){27                             System.out.printf("%d %d",i+1,temp+1);28                             System.out.println();29                         }30                     }31                 }32             }33         }       34     }35 }