205. Isomorphic Strings - LeetCode

Question

205. Isomorphic Strings

Solution

題目大意:判斷兩個字符串是否具備相同的結構

思路:構造一個map,存儲每一個字符的差,遍歷字符串,判斷兩個兩個字符串中相同位置字符的差是否相同

Java實現:

public boolean isIsomorphic(String s, String t) {
    Map<String, Integer> map = new HashMap<>();
    for (int i=0; i<s.length(); i++) {
        char c1 = s.charAt(i);
        char c2 = t.charAt(i);
        String key1 = "s_" + c1;
        String key2 = "t_" + c2;
        if (map.get(key1) == null) {
            map.put(key1, c1 - c2);
        } else if (map.get(key1) != c1 - c2) {
            return false;
        }
        if (map.get(key2) == null) {
            map.put(key2, c2 - c1);
        } else if (map.get(key2) != c2 - c1) {
            return false;
        }
    }
    return true;
}

別人的實現:

public boolean isIsomorphic(String s1, String s2) {
    int[] m = new int[512];
    for (int i = 0; i < s1.length(); i++) {
        if (m[s1.charAt(i)] != m[s2.charAt(i)+256]) return false;
        m[s1.charAt(i)] = m[s2.charAt(i)+256] = i+1;
    }
    return true;
}