<String> 345 205

345. Reverse Vowels of a String

头尾指针开始扫描。

String.contains(char)

class Solution {
    public String reverseVowels(String s) {
        if(s == null || s.length() == 0) return s;
        String vowels = "aeiouAEIOU";
        char[] chars = s.toCharArray();
        int start = 0;
        int end = s.length() - 1;

        while(start < end){
            while(start < end && !vowels.contains(chars[start]+""))
                start++;
            while(start < end && !vowels.contains(chars[end]+""))
                end--;
            char temp = chars[start];
            chars[start] = chars[end];
            chars[end] = temp;

            start++;
            end--;
        }
        return new String(chars);
    }
}

205. Isomorphic Strings

数组下标可用字母

class Solution {
    public boolean isIsomorphic(String s, String t) {
        int[] m = new int[512];
        for(int i = 0; i < s.length(); i++){
            if(m[s.charAt(i)] != m[t.charAt(i) + 256]) return false;
            m[s.charAt(i)] = m[t.charAt(i) + 256] = i + 1;
        }
        return true;
    }
}