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(难度Medium)Problem 91. Decode Ways(解码的可能性)

链接

Decode Ways - LeetCode

难度等级

Medium

题干

A message containing letters from A-Z is being encoded to numbers using the following mapping:

‘A’ -> 1
‘B’ -> 2
…
‘Z’ -> 26

Given a non-empty string containing only digits, determine the total number of ways to decode it.

题意

众所周知,我们可以用hash算法可以把英文字母hash成1-26的数字。

我们先把一个字符串hash成数字串,比如abc变成123。给定hash之后的数字串,询问它可能是多少个字符串hash之后的结果?

样例

Example 1:

**Input:** “12”
**Output:** 2
**Explanation:** It could be decoded as “AB” (1 2) or “L” (12).

Example 2:

**Input:** “226”
**Output:** 3
**Explanation:** It could be decoded as “BZ” (2 26), “VF” (22 6), or “BBF” (2 2 6).

题解

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