题解 | #出现一次的牛#
出现一次的牛
https://www.nowcoder.com/practice/ed54a59697a244d2a3c656191d575f22
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 nums int整型一维数组 * @return int整型 */ public int findSingleCow (List<int> nums) { // write code here Dictionary<int,int> res = new Dictionary<int,int>(); foreach(int num in nums) { if(res.ContainsKey(num)) { if(res[num]==1) { res[num]++; } else { res.Remove(num); } } else { res.Add(num, 1); } } ICollection<int> keys = res.Keys; foreach (int key in keys) { return key; } return -1; } }