如何输出第n行

#include<bits/stdc++.h>
using namespace std;
int a[21][21];
int main()
{
    int n;
    cin >> n;
    for(int i = 1; i <= n; i++)
        a [i][1] = a[i][i] = 1;
    for(int i = 1; i <= n; i++)
        for(int j = 2; j < i; j++)
            a[i][j] = a[i-1][j] + a[i-1][j-1];
    for(int i = 1; i <= n;i++)
    {
        for(int j = 1; j <= i;j++)
        cout << a[i][j] << " "; 
        cout << "\n";
    }
}