杨辉三角

#include<stdio.h>//杨辉三角
#include <iostream>
#include<string.h>
#include <algorithm>
using namespace std;
int main()
{
    int j, i, k, n = 0, a[20][20];
    while (n <= 0 || n >= 20)
    {
        printf("请输入要打的行数：");
        scanf_s("%d", &n);
    }
    for (i = 1; i <= n; i++)
    {
        a[i][1] = a[i][i] = 1;
    }
    for (i = 3; i <= n; i++)
    {
        for (j = 2; j <= i - 1; j++)
        {
            a[i][j] = a[i - 1][j - 1] + a[i - 1][j];
        }
    }
    for (i = 1; i < n; i++)
    {
        for (k = 1; k <= n - i; k++)
        {
            printf("  ");
        }
        for (j = 1; j <= i; j++)
        {
            printf("%6d", a[i][j]);
        }
        printf("\n");
    }
}