🐜 Study: 등대 (#46)

Author: ing-eoking

ing-eoking/등대.cc

@@ -0,0 +1,44 @@
+#include <iostream>
+#include <string>
+#include <vector>
+#include <set>
+#include <algorithm>
+
+using namespace std;
+
+#define INF 999999
+#define ROOT 1
+
+vector<set<int>> edge;
+vector<vector<int>> dp;
+
+void makeTree(int cur, int parent) {
+    edge[cur].erase(parent);
+    for (auto i : edge[cur]) {
+        makeTree(i, cur);
+    }
+}
+
+void dfs (int cur) {
+    int sum1 = 0, sum2 = 0;
+    for (auto i : edge[cur]) {
+        dfs(i);
+        dp[cur][0] += min(dp[i][0], dp[i][1]);
+        dp[cur][1] += dp[i][0];
+    }
+    dp[cur][0]++;
+}
+
+int solution(int n, vector<vector<int>> lighthouse) {
+    int answer = 0;
+    edge = vector<set<int>>(n + 1);
+    dp = vector<vector<int>> (n + 1, vector<int>(2, 0));
+    for (auto i : lighthouse) {
+        edge[i[0]].insert(i[1]);
+        edge[i[1]].insert(i[0]);
+    }
+    makeTree(ROOT, 0);
+    dfs(ROOT);
+    
+    return min(dp[ROOT][0], dp[ROOT][1]);
+}