[LeetCode]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.

class MinStack {
  Stack<Integer> stack = new Stack<>();
  Stack<Integer> minStack = new Stack<>();

  public void push(int x) {
    stack.push(x);
    if (minStack.isEmpty() || minStack.peek() >= x) {
      minStack.push(x);
    }
  }

  public void pop() {
    if (stack.pop()==minStack.peek()) minStack.pop();
  }

  public int top() {
    return stack.peek();
  }

  public int getMin() {
    return minStack.peek();
  }
}

[LeetCode]Min Stack

原文：http://blog.csdn.net/guorudi/article/details/43987417