Number of Strings Which Can Be Rearranged to Contain Substring - Practice Coding | SlaveCode
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2930. Number of Strings Which Can Be Rearranged to Contain Substring
Medium
30 Points
Math
Dynamic Programming
Combinatorics
You are given an integer n.
A string s is called good if it contains only lowercase English characters and it is possible to rearrange the characters of s such that the new string contains "leet" as a substring.
For example:
Return the total number of good strings of length n.
Since the answer may be large, return it modulo 109 + 7.
A substring is a contiguous sequence of characters within a string.
Examples
Example 1
Input: n = 4
Output: 12
Explanation: The 12 strings which can be rearranged to have "leet" as a substring are: "eelt", "eetl", "elet", "elte", "etel", "etle", "leet", "lete", "ltee", "teel", "tele", and "tlee".
Example 2
Input: n = 10
Output: 83943898
Explanation: The number of strings with length 10 which can be rearranged to have "leet" as a substring is 526083947580. Hence the answer is 526083947580 % (109 + 7) = 83943898.
Constraints
1 <= n <= 105
2930. Number of Strings Which Can Be Rearranged to Contain Substring
Medium
30 Points
Math
Dynamic Programming
Combinatorics
You are given an integer n.
A string s is called good if it contains only lowercase English characters and it is possible to rearrange the characters of s such that the new string contains "leet" as a substring.
For example:
Return the total number of good strings of length n.
Since the answer may be large, return it modulo 109 + 7.
A substring is a contiguous sequence of characters within a string.
Examples
Example 1
Input: n = 4
Output: 12
Explanation: The 12 strings which can be rearranged to have "leet" as a substring are: "eelt", "eetl", "elet", "elte", "etel", "etle", "leet", "lete", "ltee", "teel", "tele", and "tlee".
Example 2
Input: n = 10
Output: 83943898
Explanation: The number of strings with length 10 which can be rearranged to have "leet" as a substring is 526083947580. Hence the answer is 526083947580 % (109 + 7) = 83943898.