Write a Program to Find Unique Binary String

# 884. Find Unique Binary String

Given an array of strings nums containing n unique binary strings each of length n, return a binary string of length n that does not appear in nums. If there are multiple answers, you may return any of them.

### Example 1:
```
Input: nums = ["01","10"]
Output: "11"
Explanation: "11" does not appear in nums. "00" would also be correct.
```

### Example 2:
```
Input: nums = ["00","01"]
Output: "11"
Explanation: "11" does not appear in nums. "10" would also be correct.
 ```

Constraints:
```
n == nums.length
1 <= n <= 16
nums[i].length == n
nums[i] is either '0' or '1'.
All the strings of nums are unique.
```

/**
 * @param {string[]} nums
 * @return {string}
 */
 var findDifferentBinaryString = function(nums) {
    let out = '';
    for (let i = 0; i < nums.length; i++) {  
        const item = nums[i];
        out += item[i] === '0' ? '1' : '0';
    } 
    return out;   
};