TriangleSnail2.java

package basic;

class TriangleSnail2 {
    public int[] solution(int n) {
        int[] answer = new int[(n*(n+1))/2];
        int[][] matrix = new int[n][n];

        int x = -1, y = 0;
        int num = 1;

        for (int i = 0; i < n; ++i) {
            for (int j = i; j < n; ++j) {
                if (i % 3 == 0) {
                    ++x;
                } else if (i % 3 == 1) {
                    ++y;
                } else if (i % 3 == 2) {
                    --x;
                    --y;
                }
                matrix[x][y] = num++;
            }
        }

        int k = 0;
        for(int i = 0; i < n; ++i) {
            for(int j = 0; j < n; ++j) {
                if(matrix[i][j] == 0) break;
                answer[k++] = matrix[i][j];
            }
        }

        return answer;
    }
}