题解 | #牛牛出入圈#

using System;
using System.Collections.Generic;


class Solution {
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     *
     * @param enter int整型一维数组
     * @param leave int整型一维数组
     * @return bool布尔型
     */
    public bool validateCowCircle (List<int> enter, List<int> leave) {
        // write code here
        Stack<int> stack = new Stack<int>();
        int i = 0;
        int j = 0;
        while (i < enter.Count) {
            if (stack.Count != 0 && stack.Peek() == leave[j]) {
                stack.Pop();
                j++;
                continue;
            }
            if (enter[i] != null) {
                stack.Push(enter[i]);
                i++;
            }
        }
        while (j < leave.Count) {
            if (stack.Count != 0 && stack.Peek() == leave[j]) {
                stack.Pop();
                j++;
            } else {
                return false;
            }

        }
        return true;
    }
}