# Super Easy Accepted Solution.Detailed comments. 11ms. O(n) time & O(1) space.

• The idea is really easy.
First set answer to be 1, the very first positive number.
search the array for this "ans". If found, ans increments by 1.

``````// Time: O(n);
// space: O(1);
public class Solution {
public int firstMissingPositive(int[] nums) {
// initialize the ans to be the first positive number: 1
int ans = 1;
// if ans is found in the array nums.
while (findNumber(ans,nums)){
// increment ans to see if the new ans exists
ans++;
}
return ans;
}

// helper function to check through the nums to see if target number exists.
private boolean findNumber(int num,int[] nums){
// iterate through the array to see if num exists
for (int n : nums){
if (n == num){
return true;
}
}
return false;
}
}
``````

• This is O(n2) solution, for each positive number you iterated through the entire array, so it's n * n.

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