[LeetCode/Easy] 118. Pascal's Triangle

1. Input

1) int numRows

 

2. Output

1) numRows층으로 구성된 파스칼 삼각형을 리스트의 리스트로 반환

 

3. Constraint

1) 1 <= numRows <= 30

 

4. Example

Input: numRows = 5 -> Output: [[1],[1,1],[1,2,1],[1,3,3,1],[1,4,6,4,1]]

 

5. Code

1) 첫 코드(2023/05/12)

class Solution {
    public List<List<Integer>> generate(int numRows) {
        int[][] triangle = new int[numRows][numRows];
        for(int[] a : triangle)
            Arrays.fill(a, 1);
        for(int i=2 ; i<triangle.length ; i++)
            for(int j=1 ; j<i ; j++)
                triangle[i][j] = triangle[i-1][j-1] + triangle[i-1][j];
        List<List<Integer>> answer = new ArrayList<List<Integer>>();
        for(int i=0 ; i<numRows ; i++){
            List<Integer> list = new ArrayList<>();
            for(int j=0 ; j<=i ; j++)
                list.add(triangle[i][j]);
            answer.add(list);
        }
        return answer;
    }
}