我正在为决赛做研究，但无法弄清楚这个问题:
答案是C，但我不确定如何得出该结论
最佳答案
好的，所以程序总是按该顺序推0-9，因此，查看每一行，我们可以得出推和弹出发生的顺序
**The first line.** - Stack is
Pushes 0, 1, 2, 3, 4 - [0, 1, 2, 3, 4]
Pops 4, 3, 2, 1, 0 - []
Pushes 5, 6, 7, 8, 9 - [5, 6, 7, 8, 9]
Pops 9, 8, 7, 6, 5 - []
**Second line** - Stack is
Pushes 0, 1, 2 - [0, 1, 2]
Pops 2, 1 - [0]
Pushes 3, 4 - [0, 3, 4]
Pops 4, 3 - [0]
Pushes 5, 6 - [0, 5, 6]
Pops 6, 5 - [0]
Pushes 7, 8 - [0, 7, 8]
Pops 8, 7 - [0]
Pushes 9 - [0, 9]
Pops 9, 0 - []
**Third line** - Stack is
Pushes 0 - [0]
Pops 0 - []
Pushes 1, 2, 3, 4 - [1, 2, 3, 4]
Pops 4, - [1, 2, 3]
Pushes 5, 6 - [1, 2, 3, 5, 6]
Pops 6, 5, 3 - [1, 2]
Pushes 7, 8 - [1, 2, 7, 8]
Pops 8 - [1, 2, 7]
Pops ?
下一个pop 必须必须为7，因为它在8之前被推送，因此不能为1。