LeetCode - Algorithms - 155. Min Stack

The solution of two stack is clear for me.

Java

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class MinStack {
	private Stack<Integer> stack;
	private Stack<Integer> minStack;

    /** initialize your data structure here. */
    public MinStack() {
    	stack = new Stack<Integer>();
    	minStack = new Stack<Integer>();
    }

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

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

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

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

/**
 * 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();
 */

Submission Detail

  • 18 / 18 test cases passed.
  • Runtime: 64 ms
  • Your runtime beats 96.51 % of java submissions.

JavaScript

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/**
 * initialize your data structure here.
 */
var MinStack = function(stk,minStk) {
	this.stk = [];
	this.minStk = [];    
};

/**
 * @param {number} x
 * @return {void}
 */
MinStack.prototype.push = function(x) {
    this.stk.push(x);
    if (this.minStk.length==0 || this.minStk[this.minStk.length-1]>=x)
    	this.minStk.push(x);
};

/**
 * @return {void}
 */
MinStack.prototype.pop = function() {
    var x = this.stk.pop();
    if (x==this.minStk[this.minStk.length-1])
    	this.minStk.pop();
};

/**
 * @return {number}
 */
MinStack.prototype.top = function() {
    return this.stk[this.stk.length-1];
};

/**
 * @return {number}
 */
MinStack.prototype.getMin = function() {
    return this.minStk[this.minStk.length-1];
};

/**
 * Your MinStack object will be instantiated and called as such:
 * var obj = Object.create(MinStack).createNew()
 * obj.push(x)
 * obj.pop()
 * var param_3 = obj.top()
 * var param_4 = obj.getMin()
 */

Submission Detail

  • 18 / 18 test cases passed.
  • Runtime: 68 ms
  • Your runtime beats 100.00 % of javascript submissions.

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