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Java-based LeetCode algorithm problem solutions, regularly updated
2266\. Count Number of Texts
Medium
Alice is texting Bob using her phone. The **mapping** of digits to letters is shown in the figure below.
In order to **add** a letter, Alice has to **press** the key of the corresponding digit `i` times, where `i` is the position of the letter in the key.
* For example, to add the letter `'s'`, Alice has to press `'7'` four times. Similarly, to add the letter `'k'`, Alice has to press `'5'` twice.
* Note that the digits `'0'` and `'1'` do not map to any letters, so Alice **does not** use them.
However, due to an error in transmission, Bob did not receive Alice's text message but received a **string of pressed keys** instead.
* For example, when Alice sent the message `"bob"`, Bob received the string `"2266622"`.
Given a string `pressedKeys` representing the string received by Bob, return _the **total number of possible text messages** Alice could have sent_.
Since the answer may be very large, return it **modulo** 109 + 7.
**Example 1:**
**Input:** pressedKeys = "22233"
**Output:** 8
**Explanation:**
The possible text messages Alice could have sent are:
"aaadd", "abdd", "badd", "cdd", "aaae", "abe", "bae", and "ce".
Since there are 8 possible messages, we return 8.
**Example 2:**
**Input:** pressedKeys = "222222222222222222222222222222222222"
**Output:** 82876089
**Explanation:** There are 2082876103 possible text messages Alice could have sent.
Since we need to return the answer modulo 109 + 7, we return 2082876103 % (109 + 7) = 82876089.
**Constraints:**
* 1 <= pressedKeys.length <= 105
* `pressedKeys` only consists of digits from `'2'` - `'9'`.