JS简易实现“最小栈”

function MinStack() {
  this.stack = [];
  this.helperStack = [];
  this.len = 0;
  this.helperLen = 0;
}

MinStack.prototype.push = function(v) {
  this.stack.push(v);
  this.len++;

  if (!this.helperLen || this.helperStack[this.helperLen - 1] >= v) {
    this.helperStack.push(v);
    this.helperLen++;
  }
};

MinStack.prototype.pop = function() {
  if (this.stack.pop() === this.helperStack[this.helperLen - 1]) {
    this.helperStack.pop();
    this.helperLen--;
  }
  this.len--;
};

MinStack.prototype.peek = function() {
  return this.stack[this.len - 1];
};

MinStack.prototype.getMin = function() {
  return this.helperStack[this.helperLen - 1];
};

这种实现方式主要是借助更多的空间来换取时间性能的提升，借助辅助栈单纯保存比辅助栈内已有元素更小的值（元素）。