Given three integers x, y, and z, the task is to find the sum of all the numbers formed by
having 4 at most x times, having 5 at most y times, and having 6 at most z times as a digit.
Note: Output the sum modulo 10^{9}+7.
Example 1:
Input: X = 1, Y = 1, Z = 1
Output: 3675
Explanation: 4 + 5 + 6 + 45 + 54 + 56
+ 65 + 46 + 64 + 456 + 465
+ 546 + 564 + 645 + 654 = 3675
Example 2:
Input: X = 0, Y = 0, Z = 0
Output: 0
Explanation: No number can be formed
Your Task:
You don't need to read input or print anything. Complete the function getSum() which takes X, Y and Z as input parameters and returns the integer value
Expected Time Complexity: O(XYZ)
Expected Auxiliary Space: O(XYZ)
Constraints:
0 ≤ X, Y, Z ≤ 60

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