First Missing Positive Leetcode

Given an unsorted integer array, find the first missing positive integer.

For example,
Given [1,2,0] return 3,
and [3,4,-1,1] return 2.

Your algorithm should run in O(n) time and uses constant space.

My Solution:

public class Solution {    public int firstMissingPositive(int[] A) {        Boolean[] table = new Boolean[A.length + 1];        for (int i = 0; i < table.length; i++) {        table[i] = false;        }        int i = 0;        while(i < A.length){            if(A[i] > 0 && A[i] <= table.length - 1) table[A[i]] = true;            i ++;        }        i = 1;        while(i < table.length && table[i]) i++;        return i;    }}

better Solution:

public class Solution {    public int firstMissingPositive(int[] A) {        int i = 0;        while(i < A.length){            if(A[i] == i+1 || A[i] <= 0 || A[i] > A.length) i++;            else if(A[A[i]-1] != A[i]) swap(A, i, A[i]-1);            else i++;        }        i = 0;        while(i < A.length && A[i] == i+1) i++;        return i+1;    }        private void swap(int[] A, int i, int j){        int temp = A[i];        A[i] = A[j];        A[j] = temp;    }}