11.最小栈

题目

思路

维护两个栈，一个栈正常push元素，另一个栈维护每个元素为栈顶元素时的最小栈元素值。

stack1.push(x);
val = x < minStack.top()?x:minStack.top();

题解

class MinStack {
    stack<int> minStack;
    stack<int> stack1;
    int val = INT_MAX;
public:
    MinStack() {
     
        minStack.push(INT_MAX);
    }
    
    void push(int x) {
        //push元素的时候 也维护当前栈的最小值
        stack1.push(x);
        val = x < minStack.top()?x:minStack.top();
        minStack.push(val);
    }
    
    void pop() {
        stack1.pop();
        minStack.pop();
    }
    
    int top() {
        return stack1.top();
    }
    
    int getMin() {
        return minStack.top();
    }
};

/**
 * 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();
 */