LeetCode (Min Stack)

最新推荐文章于 2024-03-14 19:49:53 发布

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最新推荐文章于 2024-03-14 19:49:53 发布

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分类专栏： C++

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本文介绍了一种特殊的数据结构——最小值栈的设计方法，该栈能在常数时间内完成压栈、弹栈、获取栈顶元素及获取当前栈中最小元素的操作。通过使用两个栈结构，实现了高效的内存管理和数据检索。

Problem:

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.

Example:

MinStack minStack = new MinStack();
minStack.push(-2);
minStack.push(0);
minStack.push(-3);
minStack.getMin();   --> Returns -3.
minStack.pop();
minStack.top();      --> Returns 0.
minStack.getMin();   --> Returns -2.

Solution:

class MinStack {
private:
    stack<int> s1;
    stack<int> s2;
public:
    /** initialize your data structure here. */
    MinStack() {
        
    }
    
    void push(int x) {
        s1.push(x);
        if(s2.empty() || x <= getMin())
            s2.push(x);
    }
    
    void pop() {
        if(s1.top() == getMin()) 
            s2.pop();
        s1.pop();
    }
    
    int top() {
        return s1.top();
    }
    
    int getMin() {
        return s2.top();
    }
};

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