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