Class Solution
Medium
Given the integers zero
, one
, low
, and high
, we can construct a string by starting with an empty string, and then at each step perform either of the following:
- Append the character
'0'
zero
times. - Append the character
'1'
one
times.
This can be performed any number of times.
A good string is a string constructed by the above process having a length between low
and high
( inclusive ).
Return the number of different good strings that can be constructed satisfying these properties. Since the answer can be large, return it modulo 109 + 7
.
Example 1:
Input: low = 3, high = 3, zero = 1, one = 1
Output: 8
Explanation:
One possible valid good string is “011”.
It can be constructed as follows: "" -> “0” -> “01” -> “011”.
All binary strings from “000” to “111” are good strings in this example.
Example 2:
Input: low = 2, high = 3, zero = 1, one = 2
Output: 5
Explanation: The good strings are “00”, “11”, “000”, “110”, and “011”.
Constraints:
1 <= low <= high <= 105
1 <= zero, one <= low
-
Constructor Summary
-
Method Summary
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
-
Constructor Details
-
Solution
public Solution()
-
-
Method Details
-
countGoodStrings
public int countGoodStrings(int low, int high, int zero, int one)
-