[20251002] BOJ / G3 / 개구리 점프 / 한종욱

Author: Ukj0ng

Ukj0ng/202510/02 BOJ G3 개구리 점프.md

@@ -0,0 +1,105 @@
+```
+import java.io.*;
+import java.util.Arrays;
+import java.util.StringTokenizer;
+
+public class Main {
+    private static final BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+    private static final BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
+    private static int[][] trees, queries;
+    private static int[] uf, size;
+    private static int N, Q;
+
+    public static void main(String[] args) throws IOException {
+        init();
+        unionFind();
+
+        for (int[] query : queries) {
+            if (uf[query[0]] == uf[query[1]]) bw.write("1" + "\n");
+            else bw.write("0" + "\n");
+        }
+        bw.flush();
+        bw.close();
+        br.close();
+    }
+
+    private static void init() throws IOException {
+        StringTokenizer st = new StringTokenizer(br.readLine());
+        N = Integer.parseInt(st.nextToken());
+        Q = Integer.parseInt(st.nextToken());
+
+        trees = new int[N+1][3];
+        queries = new int[Q][2];
+        uf = new int[N+1];
+        size = new int[N+1];
+
+
+        for (int i = 1; i <= N; i++) {
+            st = new StringTokenizer(br.readLine());
+            int x1 = Integer.parseInt(st.nextToken());
+            int x2 = Integer.parseInt(st.nextToken());
+            int y = Integer.parseInt(st.nextToken());
+
+            trees[i][0] = x1;
+            trees[i][1] = x2;
+            trees[i][2] = i;
+
+            uf[i] = i;
+            size[i] = 1;
+        }
+
+        for (int i = 0; i < Q; i++) {
+            st = new StringTokenizer(br.readLine());
+            int start = Integer.parseInt(st.nextToken());
+            int end = Integer.parseInt(st.nextToken());
+
+            queries[i][0] = start;
+            queries[i][1] = end;
+        }
+
+        Arrays.sort(trees, (o1, o2) -> {
+            if (o1[0] == o2[0]) return Integer.compare(o1[1], o2[1]);
+            return Integer.compare(o1[0], o2[0]);
+        });
+    }
+
+    private static void unionFind() {
+        int maxEnd = trees[1][1];
+        int start = 1;
+
+        for (int i = 2; i <= N; i++) {
+            if (valid(maxEnd, trees[i][0])) {
+                union(trees[start][2], trees[i][2]);
+            } else {
+                start = i;
+            }
+            maxEnd = Math.max(maxEnd, trees[i][1]);
+        }
+    }
+
+    private static boolean valid(int x2, int x3) {
+        return x2 >= x3;
+    }
+
+    private static void union(int x, int y) {
+        int X = find(x);
+        int Y = find(y);
+
+        if (X == Y) return;
+
+        if (size[X] < size[Y]) {
+            uf[X] = Y;
+            size[Y] += size[X];
+        } else {
+            uf[Y] = X;
+            size[X] += size[Y];
+        }
+    }
+
+    private static int find(int x) {
+        if (uf[x] == x) return x;
+
+        return uf[x] = find(uf[x]);
+    }
+}
+```