题解 | #用两个栈实现队列#

var stack1 = []
var stack2 = []

function push(node)
{
    stack1.push(node)
}
function pop()
{   
    if(!stack2.length){
        if(stack1.length == 0)
          return null;
        while(stack1.length){
            stack2.push(stack1.pop())
        }
    }
    return stack2.pop()
}
module.exports = {
    push : push,
    pop : pop
};