题解 | #检测循环依赖#

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 prerequisites int整型二维数组
     * @param n int整型
     * @return int整型一维数组
     */
    public List<int> findOrder (List<List<int>> prerequisites, int n) {
        // write code here
        if (prerequisites == null || prerequisites.Count == 0 || n == 0)
            return null;
        List<int> lsN = new List<int>();
        List<int> lsNS = new List<int>();
        List<int> lsNE = new List<int>();
        for (int i = 0; i < prerequisites.Count; i++) {
            lsNS.Add(prerequisites[i][1]);
            lsNE.Add(prerequisites[i][0]);
        }
        List<int> lsNFind = lsNS.FindAll(r => !lsNE.Contains(r));
        if (lsNFind == null || lsNFind.Count == 0)
            return new List<int>();
        lsNS.AddRange(lsNFind);
        for (int k = 0; k < n; k++) {
            if (lsN.Contains(k))
                continue;
            lsN.Add(k);
        }
        return lsN;
    }
}