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问题
给定两个字符串 s 和 t ,编写一个函数来判断 t 是否是 s 的一个字母异位词。
输入: s = "anagram", t = "nagaram"
输出: true
输入: s = "rat", t = "car"
输出: false
说明:你可以假设字符串只包含小写字母。
进阶:如果输入字符串包含 unicode 字符怎么办?你能否调整你的解法来应对这种情况?
Given two strings s and t , write a function to determine if t is an anagram of s.
Input: s = "anagram", t = "nagaram"
Output: true
Input: s = "rat", t = "car"
Output: false
Note:You may assume the string contains only lowercase alphabets.
Follow up:What if the inputs contain unicode characters? How would you adapt your solution to such case?
示例
public class Program {
public static void Main(string[] args) {
string s = "anagram";
string t = "nagaram";
var res = IsAnagram(s, t);
Console.WriteLine(res);
s = "rat";
t = "car";
res = IsAnagram2(s, t);
Console.WriteLine(res);
s = "program";
t = "pragrom";
res = IsAnagram3(s, t);
Console.WriteLine(res);
s = "var";
t = "char";
res = IsAnagram4(s, t);
Console.WriteLine(res);
Console.ReadKey();
}
private static bool IsAnagram(string s, string t) {
//排序比较法
if(s.Length != t.Length) return false;
var s2 = s.ToList();
s2.Sort();
var t2 = t.ToList();
t2.Sort();
for(var i = 0; i < s2.Count; i++) {
if(s2[i] != t2[i]) return false;
}
return true;
}
private static bool IsAnagram2(string s, string t) {
//数组记录法
var s2 = new int[26];
var t2 = new int[26];
foreach(var c in s) {
s2[c - 97]++;
}
foreach(var c in t) {
t2[c - 97]++;
}
for(var i = 0; i < 26; i++) {
if(s2[i] != t2[i]) return false;
}
return true;
}
private static bool IsAnagram3(string s, string t) {
//IsAnagram2的变种优化写法
var s2 = new int[26];
foreach(var c in s) {
s2[c - 97]++;
}
foreach(var c in t) {
s2[c - 97]--;
}
foreach(var item in s2) {
if(item != 0) return false;
}
return true;
}
private static bool IsAnagram4(string s, string t) {
//哈希法
var dic = new Dictionary<int, int>();
foreach(var c in s) {
if(dic.ContainsKey(c - 97)) {
dic[c - 97]++;
} else {
dic[c - 97] = 1;
}
}
foreach(var c in t) {
if(dic.ContainsKey(c - 97)) {
dic[c - 97]--;
} else {
dic[c - 97] = 1;
}
}
foreach(var item in dic) {
if(item.Value != 0) return false;
}
return true;
}
}
以上给出4种算法实现,以下是这个案例的输出结果:
True
False
True
False
分析:
显而易见,IsAnagram 的时间复杂度基于所使用的排序算法,其它3种算法的时间复杂度均为: 。