155. Min Stack

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.

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class MinStack {public:    /** initialize your data structure here. */    int mimm;    stack<int> s1;    MinStack() {        mimm=INT_MAX;    }        void push(int x) {        s1.push(x);        if(x<mimm)        mimm=x;    }        void pop() {       int t=s1.top();       s1.pop();       if(t==mimm)       {           mimm=INT_MAX;           stack<int> temp;          while(!s1.empty())           {               int j=s1.top();               s1.pop();              if(j<mimm)              {                  mimm=j;              }              temp.push(j);           }           while(!temp.empty())            {                s1.push(temp.top());                temp.pop();            }       }    }        int top() {        return s1.top();    }        int getMin() {        return mimm;    }};/** * 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(); */