Count Integers :
Difficulty Level : Medium
Submissions : 145
Asked In :
Marks :20
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You are given 4 integers $$$L,R,X,Y$$$.
Your task is to count how many numbers exist between $$$L$$$ and $$$R$$$ are there (both inclusive) with given property:
The count of digits with odd frequency $$$=X$$$ and count of digits with even frequency $$$=Y$$$
Consider digits with $$$0$$$ frequency as even frequency.
Since the answer could be very large, return the answer modulo $$$10^{9}+7$$$
The input consists of 4 space separated integers as: $$$L$$$ $$$R$$$ $$$X$$$ $$$Y$$$
$$$X$$$ + $$$Y$$$ = $$$10$$$
$$$1 \le L \le R < 10^{1000} $$$
Print the count of such integers described in the above problem statement modulo $$$10^9+7$$$ .
1 1000 0 10
9
1 1000 10 0
0
In first test case where $$$L=1$$$, $$$R=1000$$$, $$$X=0$$$, $$$Y=10$$$.
Following are the solutions $$$11,22,33,44,55,66,77,88,99$$$.
All satisfy the above given property.
For Example consider $$$11$$$
| digit | frequency |
| 0 | 0 |
| 1 | 2 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 0 |
| 6 | 0 |
| 7 | 0 |
| 8 | 0 |
| 9 | 0 |
