URAL1036. Lucky Tickets

链接

dp[i][j] += dp[i-1][j-g];背包吧

数据太大了 还是JAVA好用

import java.io.*;
import java.math.*;
import java.text.*;
import java.util.*;
public class Big {
    public static void main(String[] args)
    {
        Scanner cin = new Scanner (System.in);
        BigInteger[][] dp;
        dp  = new BigInteger[55][1010];
        int i,j,g,s,n;
        n = cin.nextInt();
        s = cin.nextInt();
        for(i = 0;  i <= n ; i++)
            for(j = 0 ;j <= s ; j++)
                dp[i][j] = BigInteger.valueOf(0);
        if(s%2!=0||s/n/2>9)
        {
            System.out.println(0);
        }
        else
        {
            s/=2;
            for(i = 0 ; i <= 9 ; i++)
                dp[1][i] = BigInteger.valueOf(1);
            for(i = 2; i <= n ; i++)
            {
                for(j = 0 ; j <= s ; j++)
                {
                    for(g = 0 ; g <= 9 ; g++)
                    {
                        if(g>j) break;
                        dp[i][j]  = dp[i][j].add(dp[i-1][j-g]);
                    }
                }
            }
            BigInteger ans;
            ans = dp[n][s].multiply(dp[n][s]);
            System.out.println(ans);
        }
    }

}