题解 | 二维斐波那契数列

import java.util.*;
public class Main{
    public static void main(String[] args){
        Scanner in = new Scanner(System.in);
        int n = in.nextInt(),m = in.nextInt();
        int[][] a = new int[1050][1050];
        a[1][1] = 1;//
        for(int i=1;i<=1006;i++){
            a[1][i] = 1;
            a[i][1] = 1;
        }
        //a[2][2] = a[1][2]+a[2][1];
        for(int i=2;i<=1005;i++){
            for(int j=2;j<=1005;j++){
                a[i][j] = (a[i-1][j]+a[i][j-1])%(int)(1e9+7);
            }
        }
        System.out.println(a[n][m]);
        //a33 = a2,3+a3,2
        //a[3][2] = a[2][2] + a[3][1];
        //a23 = a1,3+a2,2
        //a13 = a1,2  a12 = a11 -> a13 = a11=1
        //a22 = a1,2+a2,1
        //a12 = a11 = 1 a21 = a11 =1
        //只要i、j其中有一个为1则结果就是1
        //aij = ai-1,j+aj-1,i;
    }
}