class Solution {
    public int missingNumber(int[] nums) {
        int count[]=new int[nums.length+1];
        
        for(int num:nums)
            count[num]++;
        
        for(int i=0; i<count.length; i++){
            if(count[i]==0)
                return i;
        }
        
        return 0;
    }
}