codingtest-java graph 전력망 둘로 나누기

Author: hangyeol0531

codingtest-java/graph/전력망을_둘로_나누기.java

@@ -0,0 +1,59 @@
+import java.util.ArrayList;
+
+public class 전력망을_둘로_나누기 {
+
+    public static ArrayList<Integer>[] tree;
+    public static boolean[] isVisited;
+    public static int total, result;
+
+    public static int solution(int n, int[][] wires) {
+
+        result = Integer.MAX_VALUE;
+        tree = new ArrayList[n + 1];
+        isVisited = new boolean[n + 1];
+        total = n;
+
+        for (int i = 1; i <= n; i++) {
+            tree[i] = new ArrayList<>();
+        }
+
+        for (int[] wire : wires) {
+            tree[wire[0]].add(wire[1]);
+            tree[wire[1]].add(wire[0]);
+        }
+
+        search(1);
+
+        return result;
+    }
+
+    public static int search(int num) {
+        isVisited[num] = true;
+        int sum = 0;
+        for (int node : tree[num]) {
+            if (!isVisited[node]) {
+                int cnt = search(node);
+                // group1(total - cnt) - group2(cnt)
+                result = Math.min(result, Math.abs(total - cnt * 2));
+                sum += cnt;
+            }
+        }
+        return sum + 1;
+    }
+
+
+    public static void main(String[] args) {
+        System.out.println(solution(
+            9,
+            new int[][]{{1, 3}, {2, 3}, {3, 4}, {4, 5}, {4, 6}, {4, 7}, {7, 8}, {7, 9}}
+        ));
+        System.out.println(solution(
+            4,
+            new int[][]{{1, 2}, {2, 3}, {3, 4}}
+        ));
+        System.out.println(solution(
+            7,
+            new int[][]{{1, 2}, {2, 7}, {3, 7}, {3, 4}, {4, 5}, {6, 7}}
+        ));
+    }
+}