leetcode-155-最小栈(java|python)

---

title: leetcode-155-最小栈(java|python)
date: 2019-09-30 13:42:04
categories:

• leetcode
  tags:
• leetcode

---

leetcode-155-最小栈(java|python)

• 设计一个支持 push，pop，top 操作，并能在常数时间内检索到最小元素的栈。

  push(x) – 将元素 x 推入栈中。
  pop() – 删除栈顶的元素。
  top() – 获取栈顶元素。
  getMin() – 检索栈中的最小元素。
  示例:

  MinStack minStack = new MinStack();
  minStack.push(-2);
  minStack.push(0);
  minStack.push(-3);
  minStack.getMin(); --> 返回 -3.
  minStack.pop();
  minStack.top(); --> 返回 0.
  minStack.getMin(); --> 返回 -2.

  来源：力扣（LeetCode）
  链接：https://leetcode-cn.com/problems/min-stack
  著作权归领扣网络所有。商业转载请联系官方授权，非商业转载请注明出处。

• class MinStack {
      int[] task1;
      int[] task2;
      int top;
      /** initialize your data structure here. */
      public MinStack() {
          task1 = new int[50];
          task2 = new int[50];
          top = 0;
      }
      
      public void push(int x) {
          if(top==task1.length){
              int[] tmp1 = new int[task1.length*2];
              int[] tmp2 = new int[task2.length*2];
              for(int i=0;i<task1.length;i++){
                  tmp1[i] = task1[i];
                  tmp2[i] = task2[i];
              }
              task1 = tmp1;
              task2 = tmp2;
          }
          task1[top]=x;
          if(top==0)
              task2[top] = x;
          else
              task2[top] = x<task2[top-1]?x:task2[top-1];
          top++;
      }
      
      public void pop() {
          if(top>=0)
              top--;
          
      }
      
      public int top() {
          if(top>=0)
              return task1[top-1];
          else
              return -1;
      }
      
      public int getMin() {
          return task2[top-1];
      }
  }
  
  /**
   * 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();
   */
  

• class MinStack {
      int[] task1;
      /** initialize your data structure here. */
      public MinStack() {
          task1 = new int[0];
      }
      
      public void push(int x) {
          int[] task3 = new int[task1.length+1];
          for(int i=0;i<task1.length;i++){
              task3[i] = task1[i];
          }
          task3[task1.length] = x;
          task1 = task3;
      }
      
      public void pop() {
          int[] task3 = new int[task1.length-1];
          for(int i=0;i<task1.length-1;i++){
              task3[i] = task1[i];
          }
          task1 = task3;
      }
      
      public int top() {
          return task1[task1.length-1];
      }
      
      public int getMin() {
          int[] task3 = new int[task1.length];
          for(int i=0;i<task1.length;i++)
              task3[i] = task1[i];
          Arrays.sort(task3);
          return task3[0];
      }
  }
  
  /**
   * 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();
   */