To determine which sequence could occur as the printed output, we can simulate the stack operations. Here is a step-by-step analysis:
- The integers 0 through 9 are pushed into the stack in order.
- The first value to be popped must be 0 since it was the first one pushed.
- After popping 0, any number from 1 to 9 can be popped next depending on subsequent operations.
Analyzing the given options: A) 1 2 3 0 6 5 4 7 8 9: This sequence is not possible because after popping 3, only numbers greater than or equal to it can be popped. So, popping of numbers like 1 and 2 before popping higher values is not possible.
B) 2 3 4 5 6 7 8 9: This sequence is possible. After popping the initial value of zero (0), all other values can be popped in ascending order.
C) 6 7 8 9 : This sequence is not possible because after popping a number, subsequent pops should have higher values. However, after popping any number less than or equal to five (5), it would not be possible to pop six (6).
D)7，8，9: This sequence is not possible because there are missing numbers that should have been popped before reaching these values.
Based on this analysis, the correct answer is B)2，3，4，5，6，7，8，9，0 ，1
内容由零声教学AI助手提供，问题来源于学员提问
