PascalTriangle.java

package com.sanket.Array;

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

/*
 Problem Link - https://leetcode.com/problems/pascals-triangle/
 Status - Accepted
 */
public class PascalTriangle {

 public static void main(String[] args) {
 int num = 3;
 generate(num);
 }

 public static List<List<Integer>> generate(int numRows) {
 List<List<Integer>> lists = new ArrayList<>();
 if (numRows < 1) { return lists; }
 List<Integer> first = new ArrayList<>();
 first.add(1);
 lists.add(first);
 int i = 1;
 while (i < numRows) {
 List<Integer> integers = new ArrayList<>();
 for (int j = 0; j <= i; j++) {
 if (j == 0 || j == i) {
 integers.add(1);
 }
 else {
 List<Integer> prev = lists.get(i - 1);
 int total = prev.get(j - 1) + prev.get(j);
 integers.add(total);
 }
 }
 lists.add(integers);
 i++;
 }
 return lists;
 }
}