9th_december.java

class BlackAndWhite
{
    //Function to find out the number of ways we can place a black and a 
    //white Knight on this chessboard such that they cannot attack each other.
    static long numOfWays(int N, int M)
    {
        // add your code here
        long ans=0L;
        long mod=1000000007;
        int[][]dirs=new int[][]{{1,2},{-1,2},{1,-2},{-1,-2},{2,1},{-2,1},{2,-1},{-2,-1}};
        for(int i=0;i<N;i++){
            for(int j=0;j<M;j++){
                long total=N*M;
                long minus=1L;
                for(int[]dir:dirs){
                    if(valid(i+dir[0],j+dir[1],N,M))minus++;
                }
                total-=minus;
                ans=(ans+total)%mod;
            }
        }
        return ans%mod;
    }
    static boolean valid(int i,int j,int n,int m){
        return i>=0 && j>=0 && i<n && j<m;
    }
}