Method dfs

solution/0400-0499/0425.Word Squares/Solution.java:50–66

(List<String> t)

    }

    private void dfs(List<String> t) {
        if (t.size() == words[0].length()) {
            ans.add(new ArrayList<>(t));
            return;
        }
        int idx = t.size();
        StringBuilder pref = new StringBuilder();
        for (String x : t) {
            pref.append(x.charAt(idx));
        }
        List<Integer> indexes = trie.search(pref.toString());
        for (int i : indexes) {
            t.add(words[i]);
            dfs(t);
            t.remove(t.size() - 1);
        }
    }
}