用函数编程计算并输出如图所示的杨辉三角，行数由用户输入。

这道题就很简单了知道杨辉三角的规律，前后都是1，中间数字等于左上加右上

杨辉三角可以通过递推公式计算：C(n, k) = C(n-1, k-1) + C(n-1, k)，其中 C(n, k) 表示第 n 行第 k 个元素。

下面给出java和c++的代码：

java:

java">import java.util.Scanner;public class PascalTriangle {public static void main(String[] args) {Scanner scanner = new Scanner(System.in);System.out.print("Enter the number of rows: ");int numRows = scanner.nextInt();scanner.close();int[][] triangle = new int[numRows][];for (int i = 0; i < numRows; i++) {triangle[i] = new int[i + 1];for (int j = 0; j <= i; j++) {if (j == 0 || j == i) {triangle[i][j] = 1;} else {triangle[i][j] = triangle[i - 1][j - 1] + triangle[i - 1][j];}System.out.print(triangle[i][j] + " ");}System.out.println();}}
}

c++代码：

#include <iostream>
#include <vector>void printPascalTriangle(int numRows) {std::vector<std::vector<int>> triangle(numRows);for (int i = 0; i < numRows; i++) {triangle[i].resize(i + 1);for (int j = 0; j <= i; j++) {if (j == 0 || j == i) {triangle[i][j] = 1;} else {triangle[i][j] = triangle[i - 1][j - 1] + triangle[i - 1][j];}std::cout << triangle[i][j] << " ";}std::cout << std::endl;}
}int main() {int numRows;std::cout << "Enter the number of rows: ";std::cin >> numRows;printPascalTriangle(numRows);return 0;
}