leetcode-946. 验证栈序列

946. 验证栈序列#

图床：blogimg/刷题记录/leetcode/946/

刷题代码汇总：https://www.cnblogs.com/geaming/p/16428234.html

题目#

思路#

使用vector模拟栈的过程

解法#

class Solution {
public:
    bool validateStackSequences(vector<int>& pushed, vector<int>& popped) {
        vector<int> tmp;
        int pos = 0;
        for(int i = 0;i<pushed.size();i++){
            tmp.push_back(pushed[i]);
            while(!tmp.empty()&&tmp[tmp.size()-1]==popped[pos]){
                tmp.pop_back();
                pos++;
            }
        }
        return tmp.empty();
    }
};

• 时间复杂度：$O(n)$，
• 空间复杂度：$O(n)$，

直接使用栈：

class Solution {
public:
    bool validateStackSequences(vector<int>& pushed, vector<int>& popped) {
        stack<int> st;
        int n = pushed.size();
        for (int i = 0, j = 0; i < n; i++) {
            st.emplace(pushed[i]);
            while (!st.empty() && st.top() == popped[j]) {
                st.pop();
                j++;
            }
        }
        return st.empty();
    }
};

补充#