4:满足x^2+y^2<=100的整数对(x,y)有多少?
key: 按照X的可能情况顺序写出:
X= Y=
1 1-9
2 1-9
3 1-9
4 1-9
5 1-8
6 1-8
7 1-7
8 1-
9 1-4 =>Myanswer:加起来=69