5. Trie树

class Trie{
    int n;
    int[][] son;
    int[] cnt;
    int idx = 0;
    Trie(int n){
        this.n = n;
        son = new int[n][26];
        cnt = new int[n];
    }

    public void insert(String s){
        char[] c = s.toCharArray();
        int p = 0;
        for (int i = 0; i < c.length; i++){
            int u = c[i] - 'a';
            if (son[p][u] == 0) son[p][u] = ++idx;
            p = son[p][u];
        }
        cnt[p]++;
    }

    public int query(String s){
        char[] c = s.toCharArray();
        int p = 0;
        for (int i = 0; i < c.length; i++){
            int u = c[i] - 'a';
            if (son[p][u] == 0) return 0;
            p = son[p][u];
        }
        return cnt[p];
    }
}