题解 | #字符个数统计#

比较麻烦的动态规划~

import java.util.Scanner;

public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        while(sc.hasNext()){
            int n = sc.nextInt();
            int m = sc.nextInt();
            int[][] matrix = new int[n + 1][m + 1];
            for(int i = 0 , j = 0; i <= m || j <= n; i ++ , j ++){
                if(i <= m){
                    matrix[n][i] = 1;
                }
                if(j <= n){
                    matrix[j][m] = 1;
                }
            }

            for(int i = n - 1; i >= 0; i --){
                for(int j = m - 1; j >= 0; j --){
                    matrix[i][j] = matrix[i + 1][j] + matrix[i][j + 1];
                }
            }
            System.out.println(matrix[0][0]);
        }
    }
}