LeetCode 6225. 差值数组不同的字符串_差值数组不同的字符串java

6225. 差值数组不同的字符串

【哈希】

class Solution {
public:
 
    // 哈希 9:19 2
 
    string f(string str) {
        string res;
        for (int i = 1; i < str.length(); i++) {
            res += str[i] - str[i - 1];
        }
        return res;
    }
 
    string oddString(vector<string>& words) {
        unordered_map<string, int> map;
        for (auto w: words) map[f(w)]++;
        for (auto w: words) {
            if (map[f(w)] == 1) return w;
        }
        return "";
    }
};

class Solution {
    public String oddString(String[] words) {
        Map<String, Integer> map = new HashMap();
        Map<String, String> ans = new HashMap();
        for (String w: words) {
            StringBuilder sb = new StringBuilder();
            int n = w.length();
            for (int i = 1; i < n; i++) {
                sb.append(String.valueOf(w.charAt(i) - w.charAt(i - 1)));
                sb.append("#");
            }
            String str = sb.toString();
            map.put(str, map.getOrDefault(str, 0) + 1);
            ans.put(str, w);
        }
        for (var k: map.keySet()) {
            if (map.get(k) == 1) return ans.get(k);
        }
        return "";
    }
}