LeetCode-in-Java
118. Pascal’s Triangle
Easy
Given an integer numRows, return the first numRows of Pascal’s triangle.
In Pascal’s triangle, each number is the sum of the two numbers directly above it as shown:
Example 1:
Input: numRows = 5
Output: [[1],[1,1],[1,2,1],[1,3,3,1],[1,4,6,4,1]]
Example 2:
Input: numRows = 1
Output: [[1]]
Constraints:
1 <= numRows <= 30
Solution
import java.util.ArrayList;
import java.util.List;
@SuppressWarnings("java:S2589")
public class Solution {
public List<List<Integer>> generate(int numRows) {
List<List<Integer>> output = new ArrayList<>();
for (int i = 0; i < numRows; i++) {
List<Integer> currRow = new ArrayList<>();
for (int j = 0; j <= i; j++) {
if (j == 0 || j == i || i <= 1) {
currRow.add(1);
} else {
int currCell = output.get(i - 1).get(j - 1) + output.get(i - 1).get(j);
currRow.add(currCell);
}
}
output.add(currRow);
}
return output;
}
}