Java Program to find out duplicate number in an Array

Problem statement : In an array 1-100, many numbers are duplicates, how do you find it?

we can loop over array and put the values in a map to find out duplicate numbers with the number of time they repeat them selves.

int[] numbers = new int [100];         Map<Integer, Integer> map = new HashMap<Integer, Integer>();                 for(int i=0;i<100;i++){             int temp = numbers[i];             Integer count = map.get(temp);             map.put(temp, (count == null) ? 1 : count + 1);         }                 for (Map.Entry<Integer, Integer> entry : map.entrySet()) {             System.out.println(“Key : ” + entry.getKey() + ” Value repetition time: “                 + entry.getValue());         }

The solution I proposed gives you the freedom of printing you data in several way or store the data in a manner which is most easy to retrieve. ie create a map for each number and save them against the key.