30.包含min函數的棧 與31.棧的壓入、彈出序列

30.包含min函數的棧

class Solution {
public:
    vector<int> vec;
    int min_val=INT_MAX,min_cnt=0;
    void push(int value) {
        vec.push_back(value);
        if(min_cnt==0){
            min_val=value,min_cnt=1;
        }
        else if(min_val>value){
            min_val=value,min_cnt=1;
        }
    }
    void pop() {
        int val=vec.back();
        vec.pop_back();
        if(min_val==val){
            min_cnt--;
        }
        if(min_cnt==0){
            min_val=INT_MAX;
            for(const int& x:vec){
                if(min_val>x){
                    min_val=x,min_cnt=1;
                }
                else if(min_val==x){
                    min_cnt++;
                }
            }
        }
    }
    int top() {
        return vec.back();
    }
    int min() {
        return min_val;
    }
};

31.棧的壓入、彈出序列

class Solution {
public:
    bool IsPopOrder(vector<int> pushV,vector<int> popV) {
        int index = 0;
        for(int i = 0; i < pushV.size(); ++i){
            s.push(pushV[i]);
            while(!s.empty() && popV[index] == s.top()){
                s.pop();
                index++;
            }
        }
        return s.empty();
    }
private:
    stack<int> s;
};