标准数独基础上，圆圈的周围不能存在圆圈里的数字。
Classic rules applied. Additionally, numbers around circle cannot exist numbers in circle.
标准数独基础上，如果圆圈格子是A，线条上有A个数字比A大。
Classic rules applied. Additionally, number A in circle, A numbers larger than A on line.
标准数独基础上，每条线条上的数字之和等于圆圈里的数字。
Classic rules applied. Additionally, the sum of numbers on each line is the numbers in circle.
填入1~5使得行列内数字不重复，每个宫内有1~5的所有数字。
Write 1~5, to make each line and column no repeated. Each box contains all numbers in 1~5.
标准数独基础上，涂色格子填入奇数。
Classic rules applied. Additionally, colored cells contain odd numbers.
标准数独基础上，框内数字是多位数质数（左→右，上→下）。
Classic rules applied. Additionally, numbers are multi-digit prime (left-right, up-down) in cage.
标准数独基础上，箭头格为N，箭头方向上不能有N。
Classic rules applied. Additionally, if the arrow cell is N, then there cannot be N on the direction the arrow points.
标准数独基础上，线条上相邻两格数字连续。
Classic rules applied. Additionally, numbers next on line are consecutive.
填入1~9使得每行列宫内数字不重复，提示表示这一方向上的摩天楼数。
Write 1~9 make numbers no repeated in each Row, Column and Box. The clue is the skyscraper number in this direciton.
从1~9中选取6种数字，使得每行、列、宫内都是这六种数字不重复，涂色格数字大于相邻白格。
Choose 6 different kind numbers from 1~9, to make each Row, Column or Box contains these 6 numbers. Colored cells are larger than the white ones adjacent to it (the rule of Fortress).
