LeetCode Min Stack

#include <iostream>

#include <cstdlib>

#include <vector>



using namespace std;



class MinStack2 {

private:

    vector<pair<int, int> > mins;

    vector<int> stack;

public:

    void push(int x) {

        stack.push_back(x);

        if (mins.size() == 0) {

            mins.push_back(make_pair(x, 1));

        } else {

            int curr_min = mins.back().first;

            if (curr_min > x) {

                mins.push_back(make_pair(x, 1));

            } else if (curr_min == x) {

                mins.back().second++;

            } else {

                // do nothing

            }

        }

    }



    void pop() {

        if (!stack.size()) {

            return;

        }

        int x = stack.back();

        stack.pop_back();

        if (x == mins.back().first) {

            if (--mins.back().second < 1) {

                mins.pop_back();

            }

        } 

    }



    int top() {

        if (!stack.size()) {

            return 0;

        }

        return stack.back();

    }



    int getMin() {

        if (!stack.size()) {

            return 0;

        }

        return mins.back().first;

    }

};





class MinStack {

private:

    vector<int> mins;

    vector<int> stack;

public:

    void push(int x) {

        stack.push_back(x);

        if (mins.size() == 0) {

            mins.push_back(x);

        } else {

            if (mins.back() >= x) {

                mins.push_back(x);

            }

        }

    }



    void pop() {

        if (!stack.size()) {

            return;

        }

        

        if (stack.back() == mins.back()) {

            mins.pop_back();

        }

        stack.pop_back(); 

    }



    int top() {

        if (!stack.size()) {

            return 0;

        }

        return stack.back();

    }



    int getMin() {

        if (!stack.size()) {

            return 0;

        }

        return mins.back();

    }

};



int main() {

    MinStack stack;

    stack.push(3);

    stack.push(2);

    stack.push(3);



    cout<<stack.getMin()<<endl;

    stack.push(1);

    stack.push(1);

    cout<<stack.getMin()<<endl;

    stack.pop();

    stack.pop();

    cout<<stack.getMin()<<endl;

    return 0;

}

同样的逻辑用java版本的就对，C++就内存超出，难道是vector默认翻倍涨的原因？

第二轮：

Design a stack that supports push, pop, top, and retrieving the minimum element in constant time.

• push(x) -- Push element x onto stack.
• pop() -- Removes the element on top of the stack.
• top() -- Get the top element.
• getMin() -- Retrieve the minimum element in the stack.

没有对连续最小值优化的版本：

// 10:26

class MinStack {

private:

    stack<int> storage;

    stack<int> mins;

public:

    void push(int x) {

        storage.push(x);

        if (mins.empty() || x <= mins.top()) {

            mins.push(x);

        }

    }



    void pop() {

        if (storage.empty()) {

            return;

        }

        int x = storage.top();

        storage.pop();

        if (x <= mins.top()) {

            mins.pop();

        }

    }



    int top() {

        return storage.top();

    }



    int getMin() {

        return mins.top();

    }

};