1980. Find Unique Binary String

Medium

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.

Example 3:

Input: nums = ["111","011","001"]
Output: "101"
Explanation: "101" does not appear in nums. "000", "010", "100", and "110" 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.

解題

func findDifferentBinaryString(nums []string) string {
    m := make(map[int]bool)

    for _, num := range nums {
        if i, err := strconv.ParseInt(num, 2, 64); err == nil {
           m[int(i)] = true // 紀錄有出現的數字
        }
    }

    str := ""
    ran := int(math.Pow(float64(2), float64(len(nums)))) // 範圍 : 0~2^len(nums)
    for i := 0; i < ran; i++ {
        if !m[i] { //一發現沒有出現過的，那就是答案
            str = strconv.FormatInt(int64(i), 2)
            break
        }
    }

    return strings.Repeat("0", len(nums) - len(str)) + str //前面要補零
}