[20251212] BOJ / P5 / 울타리 / 이종환

0224LJH/202512/12 BOJ 울타리.md

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+```java
+import java.util.*;
+import java.io.*;
+
+public class Main {
+
+    static int treeCnt, ans;
+    static Tree[] trees;
+    static Tree[] sortedByX;
+    static Tree[] sortedByY;
+
+    static class Tree {
+        int y, x, cost;
+
+        public Tree(int y, int x, int cost) {
+            this.y = y;
+            this.x = x;
+            this.cost = cost;
+        }
+    }
+
+    public static void main(String[] args) throws IOException {
+        init();
+        process();
+        print();
+    }
+
+    private static void init() throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        treeCnt = Integer.parseInt(br.readLine());
+        trees = new Tree[treeCnt];
+        ans = treeCnt-1; 
+
+        for (int i = 0; i < treeCnt; i++) {
+            StringTokenizer st = new StringTokenizer(br.readLine());
+            int x = Integer.parseInt(st.nextToken());
+            int y = Integer.parseInt(st.nextToken());
+            int cost = Integer.parseInt(st.nextToken());
+            trees[i] = new Tree(y, x, cost);
+        }
+
+        // x 기준 정렬
+        sortedByX = Arrays.copyOf(trees, treeCnt);
+        Arrays.sort(sortedByX, (a, b) -> a.x - b.x);
+
+        // y 기준 정렬
+        sortedByY = Arrays.copyOf(trees, treeCnt);
+        Arrays.sort(sortedByY, (a, b) -> a.y - b.y);
+    }
+
+    private static void process() {
+        // 모든 가능한 직사각형에 대해 시도
+        for (int i = 0; i < treeCnt; i++) {
+            for (int j = i; j < treeCnt; j++) {  
+                for (int k = 0; k < treeCnt; k++) {
+                    for (int l = k; l < treeCnt; l++) {  
+                        int minX = sortedByX[i].x;
+                        int maxX = sortedByX[j].x;
+                        int minY = sortedByY[k].y;
+                        int maxY = sortedByY[l].y;
+
+                        checkRectangle(minX, maxX, minY, maxY);
+                    }
+                }
+            }
+        }
+    }
+
+    private static void checkRectangle(int minX, int maxX, int minY, int maxY) {
+        // 둘레 계산
+        int width = maxX - minX;
+        int height = maxY - minY;
+        int perimeter = (width + height) * 2;
+
+        // 직사각형 내부의 나무들 찾기
+        List<Integer> insideCosts = new ArrayList<>();
+        int sum = 0;
+        int cutCount = 0;
+        for (int i = 0; i < treeCnt; i++) {
+            if (trees[i].x >= minX && trees[i].x <= maxX &&
+                trees[i].y >= minY && trees[i].y <= maxY) {
+                insideCosts.add(trees[i].cost);
+            } else {
+            	sum += trees[i].cost;
+            	cutCount++;
+            }
+        }
+
+        if (sum >= perimeter) {
+            ans = Math.min(ans, cutCount);
+            return;
+        }
+
+        // cost 큰 순으로 정렬
+        Collections.sort(insideCosts, Collections.reverseOrder());
+
+        for (int cost : insideCosts) {
+            sum += cost;
+            cutCount++;
+            if (sum >= perimeter) {
+                ans = Math.min(ans, cutCount);
+                break;
+            }
+        }
+    }
+
+    private static void print() {
+        System.out.println(ans);
+    }
+}
+```