Nuhman.com

public static int checkPermutation(int[] nums){
    Set<Integer> mySet = Arrays.stream(nums)
            .boxed()
            .collect(Collectors.toSet());
    for(int i=0; i<nums.length;i++){
        if(!mySet.contains(i+1)){
            return 0;
        }
    }

    return 1;
}