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  1. Prepare
  2. Algorithms
  3. Bit Manipulation
  4. Lonely Integer
  5. Discussions

Lonely Integer

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578 Discussions

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  • alban_tyrex
     + 0 comments

    Here is my c++ solution, you can watch the vidéo explanation here : https://youtu.be/E4PVCUOdeXM

        int result = 0;
    for(int x: a) result ^= x;
    return result;
}

  • emhhacker
     + 0 comments

    My Java solution with o(n) time complexity and constant space:

    public static int lonelyinteger(List<Integer> a) {
        if(a.size() == 1) return a.get(0); //only element available
        
        //use XOR to compare elements
        int res = 0;
        for(int i = 0; i < a.size(); i++) res = a.get(i) ^ res;
        return res;
    }

  • akash_prajapati6
     + 0 comments
    def lonelyinteger(a):
    for i in a:
        if(a.count(i)==1):
            return i

  • patrickgao2020
     + 0 comments

    This one is so easy! Here is my Python solution!

    def lonelyinteger(a):
    for num in a:
        if a.count(num) == 1:
            return num

  • somaditya
     + 0 comments

    Java using frequency map:

    public static int lonelyinteger(List<Integer> a) {
        if (a.size() == 1) return a.get(0);
        
        Map<Integer, Integer> map = new HashMap<>();
        
        for (int i : a) {
            map.put(i, map.getOrDefault(i, 0) + 1);
        }

        int result = 0;
        
        for (Map.Entry<Integer,Integer> e : map.entrySet()) {
            if (e.getValue() == 1) result = e.getKey();
        }
        
        return result;
    }