19926 分球

⭐️考点：数学、排列组合
🌟难度：简单
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import java.util.Arrays;
import java.util.LinkedList;
import java.util.Queue;
import java.util.Scanner;public class Main {static long[][] dp = new long[50][50];public static void main(String[] args) {Scanner sc = new Scanner(System.in);int n = sc.nextInt();int k = sc.nextInt();for(long[] x : dp){Arrays.fill(x,-1);}System.out.println(calc(n + k -1,k - 1));}static long calc(int n,int k){if(n == k || k == 0){return dp[n][k] = 1;}if(dp[n][k] != -1){return dp[n][k];}return dp[n][k] = calc(n - 1,k - 1) + calc(n - 1,k);}
}