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2014
11-18

LeetCode-Min Stack题解

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.

标签: Stack Data Structure
分析

Java代码:

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


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

    public void pop() {
        minStack.pop();
        stack.pop();
    }

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

    }

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

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