力扣 | 118. 杨辉三角

转换成一个二维数组，即可发现规律

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

public class Problem_118_Pascals_Triangle {
    public List<List<Integer>> generate(int numRows) {
        List<List<Integer>> rows = new ArrayList<>();
        for (int row = 0; row < numRows; row++) {
            List<Integer> oneRow = new ArrayList<>();
            for (int col = 0; col <= row; col++) {//对角线左边部分
                if(col == 0 || col == numRows) oneRow.add(1);
                else {
                    List<Integer> preRow = rows.get(row - 1);
                    oneRow.add(preRow.get(col - 1) + preRow.get(col));
                }
            }
            rows.add(oneRow);
        }
        return rows;
    }
 }