Longest Sealed Block

Hard

You get a string text of lowercase English letters. Call a non-empty block of consecutive characters **sealed** if it is not the whole string and every letter that appears in it appears nowhere else in text outside the block. Return the length of the longest sealed block, or -1 if there is none.

Example 1

text="xyyxzz" → 4

The block "xyyx" holds every x and y of the string and no z. The whole string does not count, and "xyyxz" fails because one z is left outside.

Example 2

text="mnmn" → -1

Any block shorter than the whole string takes an m or an n but not all of its copies.

Example 3

text="pqrp" → 2

The blocks "q", "r" and "qr" all work, and "qr" is the longest. A block with a p has to take both p's, which means the whole string.

Constraints

2 ≤ len(text) ≤ 5·10⁴
text consists of lowercase English letters

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Topics

Hash Table String Binary Search Prefix Sum

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Input

text="xyyxzz"

Expected

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