Leetcode Contains Duplicate problem solution

def containsDuplicate(self, nums: List[int]) -> bool:
        s=set()
        for ele in nums:
            if ele in s:
                return True
            else:
                s.add(ele)

public class Solution {
    public boolean containsDuplicate(int[] nums) {
        int i;
        Arrays.sort(nums);
        for(i=0;i<nums.length-1;i++)
        {
            if(nums[i]==nums[i+1])
            return true;
        }
        return false;
    }
}

class Solution {
public:
    bool containsDuplicate(vector<int>& nums) {
        unordered_map<int,int> count;
        for(auto i:nums)
            if(++count[i]>1) return true;
        return false;
    }
};

int compare(const void* a, const void* b)
{
    int l=*(int*)a;
    int p=*(int*)b;
    return (l-p);
}

bool containsDuplicate(int* nums, int numsSize) {
    qsort(nums,numsSize,sizeof(int),compare);
    
    for(int i=0;i<numsSize-1;i++)
    {
        if(nums[i]==nums[i+1])
        {
            return true;
        }
       // printf("%d==%dn",nums[i],nums[i+1]);
    }
    return false;
}