[20251211] BOJ / G5 / 전깃줄 / 한종욱

Ukj0ng/202512/11 BOJ G5 전깃줄.md

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+```
+import java.io.*;
+import java.util.*;
+
+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[][] arr;
+    private static int[] memo;
+    private static int N;
+
+    public static void main(String[] args) throws IOException {
+        init();
+        int maxLen = DP();
+
+        bw.write((N-maxLen) + "\n");
+        bw.flush();
+        bw.close();
+        br.close();
+    }
+
+    private static void init() throws IOException {
+        N = Integer.parseInt(br.readLine());
+
+        arr = new int[N][2];
+        memo = new int[N];
+
+        for (int i = 0; i < N; i++) {
+            StringTokenizer st = new StringTokenizer(br.readLine());
+            int a = Integer.parseInt(st.nextToken());
+            int b = Integer.parseInt(st.nextToken());
+
+            arr[i][0] = a;
+            arr[i][1] = b;
+        }
+
+        Arrays.sort(arr, (o1, o2) -> Integer.compare(o1[0], o2[0]));
+    }
+
+    private static int DP() {
+        int len = 0;
+
+        for (int i = 0; i < N; i++) {
+            int key = arr[i][1];
+
+            if (len == 0 || memo[len - 1] < key) {
+                memo[len] = key;
+                len++;
+            } else {
+                int index = binarySearch(len - 1, key);
+                memo[index] = key;
+            }
+        }
+
+        return len;
+    }
+
+    private static int binarySearch(int right, int key) {
+        int left = 0;
+
+        while (left < right) {
+            int mid = left + (right-left)/2;
+
+            if (memo[mid] >= key) {
+                right = mid;
+            }
+            else left = mid+1;
+        }
+
+        return right;
+    }
+}
+```