13 mong3125

mong3125/이진탐색/BOJ1300_K번째수.java

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+package 이진탐색;
+
+import java.util.Scanner;
+
+public class BOJ1300_K번째수 {
+    static int n;
+    static int k;
+    static int answer;
+    public static void main(String[] args) {
+        Scanner sc = new Scanner(System.in);
+        n = sc.nextInt();
+        k = sc.nextInt();
+
+        index(0, k);
+        System.out.println(answer);
+    }
+
+    public static void index(int front, int back) {
+        if (front > back) return;
+
+        int mid = (front + back) / 2;
+        int sum = 0;
+        for (int i = 1; i <= n; i++) {
+            sum += Math.min(mid / i, n);
+        }
+
+        if (sum < k) {
+            index(mid + 1, back);
+        } else {
+            answer = mid;
+            index(front, mid - 1);
+        }
+    }
+}

mong3125/이진탐색/BOJ2343_기타레슨.java

@@ -0,0 +1,66 @@
+package 이진탐색;
+
+import java.io.BufferedReader;
+import java.io.InputStreamReader;
+import java.io.IOException;
+import java.util.StringTokenizer;
+
+public class BOJ2343_기타레슨 {
+
+    static int N;
+    static int M;
+    static int[] lectures;
+    public static void main(String[] args) throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        StringTokenizer st = new StringTokenizer(br.readLine());
+
+        N = Integer.parseInt(st.nextToken());
+        M = Integer.parseInt(st.nextToken());
+
+        lectures = new int[N];
+        st = new StringTokenizer(br.readLine());
+
+        int sum = 0;
+        int max = 0;
+        for(int i = 0; i < N; i++) {
+            lectures[i] = Integer.parseInt(st.nextToken());
+            sum += lectures[i];
+            max = Math.max(max, lectures[i]);
+        }
+
+        // 블루레이의 크기는 max부터 sum 사이 일것이다.
+        int result = minimumBlueray(max, sum);
+
+        System.out.println(result);
+    }
+
+    public static int minimumBlueray(int start, int end) {
+        if (start < end) return -1;
+
+        int mid = (start + end) / 2;
+
+        if (can(mid)) {
+            int more = minimumBlueray(start, mid - 1);
+            return more != -1 ? more : mid;
+        }
+        else return minimumBlueray(mid + 1, end);
+    }
+
+    public static boolean can(int blueray) {
+        int count = M;
+        int i = 0;
+        int stack = blueray;
+        while (count > 0) {
+            while (stack - lectures[i] > 0) {
+                if (i == N) return true;
+                stack -= lectures[i];
+                i++;
+            }
+
+            stack = blueray;
+            count--;
+        }
+
+        return false;
+    }
+}