'commit'

TangDou/LanQiaoBei/LanQiaoSTEMA202008/DaKuoHao_2.cpp

@@ -0,0 +1,35 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+const int N = 1e5 + 10;
+
+int n;
+int res;
+
+char stk[N];
+bool check(string s) {
+    int tt = 0; // 因为是多次使用栈，所以这里tt需要每次清空为0
+    for (int i = s.size() - 1; i >= 0; i--) {
+        if (tt && stk[tt] == '}' && s[i] == '{')
+            tt--;
+        else
+            stk[++tt] = s[i];
+    }
+    return tt == 0;
+}
+
+void dfs(int u, string t) {
+    if (u == 2 * n + 1) {
+        if (check(t)) res++;
+        return;
+    }
+
+    dfs(u + 1, t + "{");
+    dfs(u + 1, t + "}");
+}
+int main() {
+    cin >> n;
+    dfs(1, "");
+    cout << res << endl;
+    return 0;
+}