fix trie

Author: mzuenni

content/string/trie.cpp

@@ -10,13 +10,14 @@ vector<node> trie = {node()};
 int traverse(const vector<int>& word, int x) {
 	int id = 0;
 	for (int c : word) {
-		if (id < 0 || (trie[id].words == 0 && x <= 0)) return -1;
+		if (trie[id].words == 0 && x <= 0) return -1;
 		trie[id].words += x;
 		if (trie[id].nxt[c] < 0 && x > 0) {
 			trie[id].nxt[c] = sz(trie);
 			trie.emplace_back();
 		}
 		id = trie[id].nxt[c];
+		if (id < 0) return -1;
 	}
 	trie[id].words += x;
 	trie[id].ends += x;
@@ -26,7 +27,6 @@ int traverse(const vector<int>& word, int x) {
 int insert(const vector<int>& word) {
 	return traverse(word, 1);
 }
-
 bool erase(const vector<int>& word) {
 	int id = traverse(word, 0);
 	if (id < 0 || trie[id].ends <= 0) return false;