Trie.cpp

const int letters = 26;
struct Node {
    vector<int> next_node;
    int is_a_leaf = 0;
    Node() {
        next_node.resize(letters);
        fill(begin(next_node), end(next_node), -1);
    }
};
struct Trie{
    vector<Node> trie_tree;
    Trie(){
        trie_tree.emplace_back();
    }
    void add_string(string &a) {
        int root_here = 0;
        for(char c : a){
            int index = c - 'a';
            if(trie_tree[root_here].next_node[index] == -1) {
                  trie_tree[root_here].next_node[index] = sz(trie_tree);
                  trie_tree.emplace_back();
            }
            root_here = trie_tree[root_here].next_node[index];
        }
        trie_tree[root_here].is_a_leaf++;
    }
};
Trie t = Trie();