31 lines
610 B
C++
31 lines
610 B
C++
#include <bits/stdc++.h>
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using namespace std;
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int n;
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int res;
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stack<char> stk;
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bool check(string t) {
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stack<char>().swap(stk);
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for (int i = t.size() - 1; i >= 0; i--) {
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if (!stk.empty() && stk.top() == '}' && t[i] == '{')
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stk.pop();
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else
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stk.push(t[i]);
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}
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return stk.size() == 0;
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}
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void dfs(int u, string t) {
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if (u == 2 * n + 1) {
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if (check(t)) res++;
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return;
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}
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dfs(u + 1, t + "{");
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dfs(u + 1, t + "}");
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}
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int main() {
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cin >> n;
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dfs(1, "");
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cout << res << endl;
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return 0;
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} |