public class FindSmallestMissingPositive {
public static void main(String args[]){
    int a[] = {3,5,4,-1,1,-1,0};
    System.out.println("Smallest Missing positive : "+ findSmPositive(a));
}

public static int findSmPositive(int input[]){
    int min = input[0];
    int max= input[0];

    HashSet<Integer> set = new HashSet<Integer>();

    for(int i=0;i<input.length;i++){
        set.add(input[i]);

        if(input[i]<min){
            min = input[i];
        }
        if(input[i]>max){
            max = input[i];
        }
    }

    for(int i=min;i<=max;i++){
        if(i>0 && !set.contains(i)){
            return i;
        }
        else continue;

    }
    return -1;
}
}