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程式語言 - LeetCode - C++ - 155. Min Stack

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題目：


解答：

class MinStack {
public:
    MinStack() {
        
    }
    
    void push(int val) {
        st.push(val);

        if (min_st.empty() || val <= min_st.top()) {
            min_st.push(val);
        }
        else {
            min_st.push(min_st.top());
        }
    }
    
    void pop() {
        st.pop();
        min_st.pop();
    }
    
    int top() {
        return st.top();
    }
    
    int getMin() {
        return min_st.top();
    }

private:
    stack<int> st;
    stack<int> min_st;
};

/**
 * Your MinStack object will be instantiated and called as such:
 * MinStack* obj = new MinStack();
 * obj->push(val);
 * obj->pop();
 * int param_3 = obj->top();
 * int param_4 = obj->getMin();
 */