Niuke.com brush questions | stack push and pop sequence

Topic source: Niuke.com
programming connection

Topic description

Input two integer sequences. The first sequence represents the stack's push sequence. Please check whether the second sequence is the stack's pop-up sequence. Assume that all numbers pushed onto the stack are not equal. For example, the sequence 1, 2, 3, 4, 5 is the push sequence of a stack, the sequence 4, 5, 3, 2, 1 is a pop sequence corresponding to the stack sequence, but 4, 3, 5, 1, 2 It cannot be the pop sequence of the push sequence. (Note: the two sequences are of equal length)

Parse:

• Use a stack to save the push data and analyze the entire push and pop process.
• Keep pushing and pushing the stack, and when the number pushed and the number popped are found to be the same, pop the number
• If the last data in the stack is 0, it means that the push and pop data are matched.

step	operate	stack	Pop up numbers	Remark
1	push in 1	1
2	Press in 2	1，2
3	Press in 3	1，2，3
4	Press in 4	1，2，3，4
5	pop up	1，2，3	4	Because it is the same as the popup number
6	Press in 5	1，2，3，5
7	pop up	1，2，3	5	Because it is the same as the popup number
8	pop up	1，2	3	Because it is the same as the popup number
9	pop up	1	2	Because it is the same as the popup number
8	pop up		1	Because it is the same as the popup number

….

Code:

class Solution {
public:
    bool IsPopOrder(vector<int> pushV,vector<int> popV) {
        stack<int> st;
        for(int i=0,j=0;i<pushV.size();i++)
        {
            for(st.push(pushV[i]);j<popV.size()&&st.top()==popV[j]&&!st.empty();st.pop(),j++);//只有在相等的时候才弹出           
        }
        return st.empty();      
    }
};