[leetcode] problem 119 – pascal’s triangle ii

Given a non-negative index k where k ≤ 33, return the kth index row of the Pascal’s triangle.

Note that the row index starts from 0.

In Pascal’s triangle, each number is the sum of the two numbers directly above it.

Example

Input: 3

Output: [1,3,3,1]

Follow up

Could you optimize your algorithm to use only O(k) extra space?

Code

public List<Integer> (int rowIndex) {
    List<Integer> triangle = new ArrayList<>();

    for (int idx = 0; idx <= rowIndex; idx++) {
        triangle.add(1);

        for (int num = idx - 1; num > 0; num--)
            triangle.set(num, triangle.get(num) + triangle.get(num - 1));
    }

    return triangle;
}

[leetcode] problem 119 – pascal’s triangle ii

Example

Follow up

Code

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