第二周白银赛杨辉三角问题

 https://vjudge.net/contest/275895#problem/C

#include <iostream>
using namespace std;
int main()
{
	int n; 
	int a[30][30];
	while (cin>>n)
	{
		for (int i = 0; i < n; i++)//先让头尾都是一
		{
			a[i][0] = 1;
			a[i][i] = 1;
			for (int i = 2; i < n; i++)//从第三行开始便有了规律
			{

				for (int j = 1; j < i; j++)
				{
					a[i][j] = a[i - 1][j - 1] + a[i - 1][j];
				}
			}
		}
		for (int i = 0; i < n; i++)
		{
			for (int j = 0; j <= i; j++)
			{
				cout << a[i][j];
				if (j!=i)
				{
					cout << " ";
				}
			}
			cout << endl;
		}
		cout << endl;
	}
}