Question

Write a method List-Double> duplicates(List<Double> input) that returns a List of all duplicates in the input List. You may assume occurs either once or twice. The expected runtime must be O(n) where n is elements (no credit for slower runtimes, so you cannot sort the input).(0 Examples: input = [3,4,4] input [3, 7,4, 7,3] return [7, 3] that each element the number of points) return [4] List Double duplicates(List<Double input)(

Answer 1

Since you have not mentioned the language of your preference, i am providing the code in Java.

Please find the code below.

CODE

public List<Double> duplicates (List<Double> input) {

Map<Double, Integer> map = new HashMap<>();

for (Double inp : input) {

if (map.containsKey(inp)) {

map.put(inp, map.get(inp) + 1);

} else {

map.put(inp, 1);

}

}

List<Double> res = new ArrayList<>();

for (Map.Entry<Double, Integer> en : map.entrySet()) {

if (en.getValue() > 1) {

res.add(en.getKey());

}

}

return res;

}