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Need Explanation of a combinatorics formulae
Suppose we want to fill one array A (which has M elements) such that the sum of the numbers is X.
X=A[1]+A[2]+A[3]....A[m] where A[i] is a non-negative numbers. The number of ways to fill this row can be obtained using a combinatorics formulae: (X+M-1) C (X-1).
Can anyone explain ? Thanks in advance.
