Leetcode题解 155. Min Stack

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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.

中规中矩，用ArrayList来做，一次AC。下次再看可以试试数组，队列等数据结构。

class MinStack {    List<Integer> mList=new ArrayList<Integer>();    int mTop=-1;    public void push(int x) {        mList.add(x);        mTop++;    }    public void pop() {        if(mList.size()>0){            mList.remove(mTop);            mTop--;        }    }    public int top() {        return mList.get(mTop);    }    public int getMin() {        int min=Integer.MAX_VALUE;        for(int i=0;i<mList.size();i++){            if(mList.get(i)<min){                min=mList.get(i);            }        }        return min;    }}

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