题解

#include <bits/stdc++.h>
using namespace std;
int n,m,a[21][21];
int main(){
cin>>n>>m;
for(int i=1;i<=n;i++)
{
for(int j=1;j<=m;j++)
{
if(i1&&j1) a[i][j]=1;
else
a[i][j]=a[i-1][j]+a[i][j-1]+a[i][j+1];
}
}
cout<<a[n][m]<<endl;
return 0;
}