nPr.cpp

// A Dynamic Programming based solution that uses
// table P[][] to calculate the Permutation Coefficient
#include<bits/stdc++.h>
 
// Returns value of Permutation Coefficient P(n, k)
int permutationCoeff(int n, int k)
{
    int P[n+1][k+1];
 
    // Caculate value of Permutation Coefficient in
    // bottom up manner
    for (int i =0; i <= n; i++)
    {
        for (int j = 0; j <= std::min(i,k); j++)
        {
            // Base Cases
            if (j == 0)
                P[i][j] = 1;
 
            // Calculate value using previosly stored values
            else
                P[i][j] = P[i-1][j] + (j*P[i-1][j-1]);
 
            // This step is important as P(i,j)=0 for j>i
            P[i][j+1] = 0;
        }
    }
    return P[n][k];
}
 
// Driver program to test above function
int main()
{
    int n = 10, k = 2;
    printf("Value of P(%d, %d) is %d ",
                        n, k, permutationCoeff(n, k) );
    return 0;
}