题解 | #设计getMin功能的栈#

import java.util.*;


public class Solution {
    /**
     * return a array which include all ans for op3
     * @param op int整型二维数组 operator
     * @return int整型一维数组
     */
    public int[] getMinStack (int[][] op) {
        int opt = 0;
        for(int i=0; i<op.length; i++)
            if(op[i].length==1 && op[i][0]==3)
                opt++;
        int[] res = new int[opt];
        int ind = 0;
        Solution stack = new Solution();
        for(int i=0; i<op.length; i++){
            if(1 == op[i][0])
                stack.push(op[i][1]);
            else if(2 == op[i][0])
                stack.pop();
            else
                res[ind++] = stack.getMin();
        }
        return res;
    }
    int[] nums = new int[8];
    int index = 0;
    public void push(int n){
        if(index == (nums.length-1)){
            nums = Arrays.copyOf(nums,nums.length*2);
        }
        nums[index++] = n;
    }
    public int pop(){
        return nums[index--];
    }
    public int getMin(){
        int min = nums[0];
        for(int i=1; i<index; i++){
            min = Math.min(min,nums[i]);
        }
        return min;
    }
}