1.两个list如果有重复元素(如List1: a,b,a List2: b,b,a) 是无法通过包含关系来判断是否相等的.
有两个办法,其一是两个List排序后再按顺序比较.另一个办法就是计算各元素的重复项再进行比较
第一种方案劣势太明显,时间复杂度过大
第二种以空间换时间,只需要遍历无需排序即可.
/// <summary> /// 判断两个集合是否是相等的(所有的元素及数量都相等) /// </summary> /// <typeparam name="T">集合元素类型</typeparam> /// <param name="sourceCollection">源集合列表</param> /// <param name="targetCollection">目标集合列表</param> /// <returns>两个集合相等则返回True,否则返回False</returns> public static bool EqualList<T>(this IList<T> sourceCollection, IList<T> targetCollection) where T : IEquatable<T> { //空集合直接返回False,即使是两个都是空集合,也返回False if (sourceCollection == null || targetCollection == null) { return false; } if (object.ReferenceEquals(sourceCollection, targetCollection)) { return true; } if (sourceCollection.Count != targetCollection.Count) { return false; } var sourceCollectionStaticsDict = sourceCollection.StatisticRepetition(); var targetCollectionStaticsDict = targetCollection.StatisticRepetition(); return sourceCollectionStaticsDict.EqualDictionary(targetCollectionStaticsDict); } /// <summary> /// 判断两个字典是否是相等的(所有的字典项对应的值都相等) /// </summary> /// <typeparam name="TKey">字典项类型</typeparam> /// <typeparam name="TValue">字典值类型</typeparam> /// <param name="sourceDictionary">源字典</param> /// <param name="targetDictionary">目标字典</param> /// <returns>两个字典相等则返回True,否则返回False</returns> public static bool EqualDictionary<TKey, TValue>(this Dictionary<TKey, TValue> sourceDictionary, Dictionary<TKey, TValue> targetDictionary) where TKey : IEquatable<TKey> where TValue : IEquatable<TValue> { //空字典直接返回False,即使是两个都是空字典,也返回False if (sourceDictionary == null || targetDictionary == null) { return false; } if (object.ReferenceEquals(sourceDictionary, targetDictionary)) { return true; } if (sourceDictionary.Count != targetDictionary.Count) { return false; } //比较两个字典的Key与Value foreach (var item in sourceDictionary) { //如果目标字典不包含源字典任意一项,则不相等 if (!targetDictionary.ContainsKey(item.Key)) { return false; } //如果同一个字典项的值不相等,则不相等 if (!targetDictionary[item.Key].Equals(item.Value)) { return false; } } return true; } /// <summary> /// 统计集合的重复项,并返回一个字典 /// </summary> /// <typeparam name="T">集合元素类型</typeparam> /// <param name="sourceCollection">统计集合列表</param> /// <returns>返回一个集合元素及重复数量的字典</returns> private static Dictionary<T, int> StatisticRepetition<T>(this IEnumerable<T> sourceCollection) where T : IEquatable<T> { var collectionStaticsDict = new Dictionary<T, int>(); foreach (var item in sourceCollection) { if (collectionStaticsDict.ContainsKey(item)) { collectionStaticsDict[item]++; } else { collectionStaticsDict.Add(item, 1); } } return collectionStaticsDict; }
2
public class CommonTest { /// <summary> /// 集合相等比较 /// </summary> [Fact] public void ListEqual_Tests() { var sourceList = new List<string>() { "a", "b", "a" }; var targetList = new List<string>() { "b", "b", "a" }; var resp = sourceList.EqualList(targetList); Assert.False(resp ); } /// <summary> /// 集合相等比较 /// </summary> [Fact] public void ListEqual2_Tests() { var sourceList = new List<string>() { "a", "b", }; var targetList = new List<string>() { "b", "a" }; var resp = sourceList.EqualList(targetList); Assert.True(resp); } }
原文地址:https://www.cnblogs.com/zhshlimi/p/8418903.html
时间: 2024-10-12 10:08:37