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Actually the answer is

(m+n-1)C(n)=(m+n-1)!/ ((m-1)!)*n!)

and the forumula

Ncr=(n-1)c(r-1)+ (n-1)c(r)

now you can apply dp you may take help of this function as it is little bit tuff for me to understand c# that's why iam writing this function

`cpp

for (i = 0; i <= n; i++) { for (j = 0; j <= k; j++) {

if (j == 0 || j == i)//as nc0=ncn=1; C[i][j] = 1; else C[i][j] = ((C[i-1][j-1])%mod +( C[i-1][j])%mod)%mod; } }

`

now you can return the desired answer .

Now in your code this line

result = (topfact / (belowfact1 * belowfact2))%1000000007; will get run-time error or tle as your modulus approach formula is not correct as

(a * b) % mod = ((a % mod) * (b % mod)) % mod, (a / b ) % mod = ((a % mod) * (b^-1 % mod)) % mod,

and one more reason is that the

(topfact / (belowfact1*belowfact2))

will not work properly .

if problem persist then feel free to contact for further

clarification or you may take help of my c code

http://ideone.com/knhd1k

....

k means m..?

## Sherlock and Permutations

You are viewing a single comment's thread. Return to all comments →

Actually the answer is

(m+n-1)C(n)=(m+n-1)!/ ((m-1)!)*n!)

and the forumula

Ncr=(n-1)c(r-1)+ (n-1)c(r)

now you can apply dp you may take help of this function as it is little bit tuff for me to understand c# that's why iam writing this function

`cpp

for (i = 0; i <= n; i++) { for (j = 0; j <= k; j++) {

`

now you can return the desired answer .

Now in your code this line

result = (topfact / (belowfact1 * belowfact2))%1000000007; will get run-time error or tle as your modulus approach formula is not correct as

(a * b) % mod = ((a % mod) * (b % mod)) % mod, (a / b ) % mod = ((a % mod) * (b^-1 % mod)) % mod,

and one more reason is that the

(topfact / (belowfact1*belowfact2))

will not work properly .

if problem persist then feel free to contact for further

clarification or you may take help of my c code

http://ideone.com/knhd1k

....

k means m..?