260120 : [BOJ 22856] 트리 순회

_munhyeong/22856.cpp

@@ -0,0 +1,75 @@
+#include <iostream>
+#include <vector>
+#include <stack>
+
+using namespace std;
+
+int find_end_node(vector<pair<int, int>>& nodes) {
+	int cur_top = 0;
+	while (true) {
+		// 1. 단 오른쪽으로 가기
+		if (nodes[cur_top].second >= 0)
+			cur_top = nodes[cur_top].second;
+		else
+			break;
+	}
+	return cur_top;
+}
+
+int dfs(vector<pair<int, int>> &nodes) {
+	int end_node = find_end_node(nodes);
+	//cout << end_node + 1 << "\n";
+
+	vector<bool> visited(nodes.size());
+	stack<int> st;
+	st.push(0);
+
+	int answer = 0;
+	while (!st.empty()) {
+		int top = st.top();
+		st.pop();
+
+		//cout << top + 1 << " ";
+		answer++;
+
+		bool is_inserted = false;
+
+		if (nodes[top].second >= 0 && !visited[nodes[top].second]) {
+			visited[nodes[top].second] = true;
+			st.push(top);
+			st.push(nodes[top].second);
+			is_inserted = true;
+		}
+
+		if (nodes[top].first >= 0 && !visited[nodes[top].first]) {
+			visited[nodes[top].first] = true;
+			st.push(top);
+			st.push(nodes[top].first);
+			is_inserted = true;
+		}
+
+		if (!is_inserted) {
+			if (top == end_node)
+				break;
+		}
+	}
+	return answer - 1;
+}
+
+int main() {
+	int N;
+	cin >> N;
+
+	vector<pair<int, int>> nodes(N);
+	for (int i = 0; i < N; i++) {
+		int a, b, c;
+		cin >> a >> b >> c;
+		a--; b--; c--;
+
+		nodes[a] = { b, c };
+	}
+
+	cout << dfs(nodes);
+
+	return 0;
+}