why does O(N^2) pass with 100%?

The problems that have more than one "trip to the icream" per test case are effing BS. Shoving more than one assert into a test case is a horrific antipattern. And having to sort this sht out here with no debugger and the output going to god knows where effing sucks. I wouldn't give a sht except job interviews make me go to this stupid site. Ef you, authors, for shoving more than one test case into a test. Seriously.

Javascript Solution

function icecreamParlor(m, arr) {
  for (let i = 0; i < arr.length; i++) {
    const remainder = m - arr[i];
    const secondIndex = arr.indexOf(remainder);
    if (secondIndex != -1 && secondIndex != i) {
      return [i+1, secondIndex+1].sort((a,b) => a - b);
    }
  }
}

public static List<Integer> icecreamParlor(int m, List<Integer> arr) {
// Write your code here
    Map<Integer, Integer> costVsIndex = new HashMap<>();
    List<Integer> result = new ArrayList<>();
    for(int i = 0; i< arr.size(); i++) {
        Integer remaining = m - arr.get(i);
        if(costVsIndex.containsKey(remaining)) {
             result.add(costVsIndex.get(remaining) + 1);
             result.add(i + 1);
        } else {
            costVsIndex.put(arr.get(i), i);
        }
    }
    return result;
}

}

I'll never understand the HackerRank trend of posting solutions in the discussion section let alone uncommented and unexplained solutions.

My thoughts: * I considered a two-pointer solution but the array isn't pre-sorted so this would require a sort which adds n * log(n) or a custom sort/search

• Alternatively, you can use memoisation (collect some info while traversing for later). You need to think about the complement of the current price and available money.

• Don't forget that the array isn't unique, just the solution