LeetCode: 242. Valid Anagram

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242. Valid Anagram

LeetCode - Valid Anagram

两种解法都可以，还是要多做题啊！

Given two strings s and t _, write a function to determine if _t is an anagram of s.

Example 1:

Input: s = "anagram", t = "nagaram"
Output: true

Example 2:

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?

思路分析

一刷
二刷

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/**
 * Runtime: 3 ms, faster than 93.97% of Java online submissions for Valid Anagram.
 *
 * Memory Usage: 36.2 MB, less than 98.06% of Java online submissions for Valid Anagram.
 *
 * @author D瓜哥 · https://www.diguage.com
 * @since 2020-01-10 23:48
 */
public boolean isAnagram(String s, String t) {
    if (Objects.isNull(s) && Objects.isNull(t)) {
        return true;
    }
    if (Objects.isNull(s) || Objects.isNull(t)) {
        return false;
    }
    int[] sChartCount = new int[26];
    for (char c : s.toCharArray()) {
        sChartCount[c - 'a']++;
    }
    int[] tChartCount = new int[26];
    for (char c : t.toCharArray()) {
        tChartCount[c - 'a']++;
    }
    return Arrays.equals(sChartCount, tChartCount);
}

/**
 * Runtime: 3 ms, faster than 93.97% of Java online submissions for Valid Anagram.
 *
 * Memory Usage: 37.9 MB, less than 64.51% of Java online submissions for Valid Anagram.
 */
public boolean isAnagramSort(String s, String t) {
    char[] sChars = s.toCharArray();
    Arrays.sort(sChars);
    char[] tChars = t.toCharArray();
    Arrays.sort(tChars);
    return Arrays.equals(sChars, tChars);
}

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/**
 * @author D瓜哥 · https://www.diguage.com
 * @since 2020-01-10 23:48
 */
public boolean isAnagram(String s, String t) {
  if (s.length() != t.length()) {
    return false;
  }
  int[] chars = new int[26];
  for (int i = 0; i < s.length(); i++) {
    char c = s.charAt(i);
    chars[c - 'a']++;
  }
  for (int i = 0; i < t.length(); i++) {
    char c = t.charAt(i);
    chars[c - 'a']--;
    if (chars[c - 'a'] < 0) {
      return false;
    }
  }
  for (int cnt : chars) {
    if (cnt != 0) {
      return false;
    }
  }
  return true;
}

参考资料

242. 有效的字母异位词 - 官方题解