回答:
1.第一个的fault应该是for(int i = x.length-1; i >0; i++)中应该改为i>=0
第二个的fault应该是for(int i = 0;i < x.length; i++)中应该改为for(int i = x.length-1; i >=0; i--)
2.test: x =[]; y = 3
test: x=[]
3.test: x = [2,3,5]; y = 3
test: x =[]
4.test: x=[2];y=3
test: x=[1,1,0]