用java写一个杨辉三角

下面是 Java 代码实现的杨辉三角：

import java.util.ArrayList;
import java.util.List;

public class PascalTriangle {
    public static void main(String[] args) {
        int rows = 5;
        List<List<Integer>> result = generate(rows);
        for (List<Integer> row : result) {
            for (Integer num : row) {
                System.out.print(num + " ");
            }
            System.out.println();
        }
    }

    public static List<List<Integer>> generate(int numRows) {
        List<List<Integer>> result = new ArrayList<>();
        if (numRows == 0) {
            return result;
        }
        List<Integer> firstRow = new ArrayList<>();
        firstRow.add(1);
        result.add(firstRow);
        for (int i = 1; i < numRows; i++) {
            List<Integer> prevRow = result.get(i - 1);
            List<Integer> currRow = new ArrayList<>();
            currRow.add(1);
            for (int j = 1; j < i; j++) {
                currRow.add(prevRow.get(j - 1) + prevRow.get(j));
            }
            currRow.add(1);
            result.add(currRow);
        }
        return result;
    }
}