Given a string S consisting of the characters 0, 1 and 2. Your task is to find the length of the smallest substring of string S that contains all the three characters 0, 1 and 2. If no such substring exists, then return -1.
Example 1:
Input:
S = "01212"
Output:
3
Explanation:
The substring 012 is the smallest substring
that contains the characters 0, 1 and 2.
Example 2:
Input:
S = "12121"
Output:
-1
Explanation:
As the character 0 is not present in the
string S, therefor no substring containing
all the three characters 0, 1 and 2
exists. Hence, the answer is -1 in this case.
Your Task:
Complete the function smallestSubstring() which takes the string S as input, and returns the length of the smallest substring of string S that contains all the three characters 0, 1 and 2.
Expected Time Complexity: O(|S|)
Expected Auxiliary Space: O(1)
Constraints:
1 ≤ |S| ≤ 10^{5}
All the characters of String S lies in the set {'0', '1', '2'}

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