箭头 Arrow

标准数独基础上，箭头上的数字之和等于圆圈里的数字。

Classic rules applied, additionally, numbers on each line sums to numbers in circle.

◆将线上格子分组，计算每个部分的极值，进而计算总体的极值。当一侧的极小是另一侧的极大时，两侧相等。

Devide the arrow lines into pieces, and discuss the max and min value of each group ,then the total. When the min of one side equals to the max of the other side, then the both sides are equal.

◆线条上数字不能与圈内数字相等，除非线条只有一格。

Numbers in circle cannot be same with numbers on line, except that the line just occupy one cell.

◆裕度，即容错度。交叉相减一侧的极小值与另一侧的极大值，其中绝对值较小的一个值即为该处的裕度。

An important definition is 裕度(margin), or fault-tolerant. Minus cross one min to the other max, the smaller absolute value is the margin of here.

计算出裕度M后，每一处的候选数在极限的情况下变化M。

Each cell's candidates will change in range of M in extreme situations.

练习 Practice

①找出问号格的值 Find out the ？cell.

② 找出下一步 Find the next hint.

答案 Answer

① C1=6; A1=6; F1=1; D1=6 ② C5=7