diff --git a/binary_search/12015/nayoung12015.java b/binary_search/12015/nayoung12015.java
new file mode 100644
index 0000000..d7125d1
--- /dev/null
+++ b/binary_search/12015/nayoung12015.java
@@ -0,0 +1,46 @@
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.util.StringTokenizer;
+
+// 풀이 참고 : https://st-lab.tistory.com/285
+
+public class nayoung12015 {
+    public static void main(String[] args) throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+
+        int N = Integer.parseInt(br.readLine());
+        StringTokenizer st = new StringTokenizer(br.readLine());
+
+        int[] A = new int[N];
+
+        for (int i = 0; i < N; i++) {
+            A[i] = Integer.parseInt(st.nextToken());
+        }
+
+        int[] LIS = new int[N];
+        LIS[0] = A[0];
+        int lengthOfLIS = 1;
+
+        for (int i = 1; i < N; i++) {
+            if (LIS[lengthOfLIS - 1] < A[i]) {
+                LIS[lengthOfLIS] = A[i];
+                lengthOfLIS++;
+            } else {
+                int lo = 0;
+                int hi = lengthOfLIS;
+
+                while (lo < hi) {
+                    int mid = (lo + hi) / 2;
+
+                    if (LIS[mid] <= A[i]) lo = mid + 1;
+                    else hi = mid;
+                }
+
+                LIS[lo] = A[i];
+            }
+        }
+
+        System.out.println(lengthOfLIS);
+    }
+}
diff --git a/binary_search/1300/nayoung1300.java b/binary_search/1300/nayoung1300.java
new file mode 100644
index 0000000..c7752cf
--- /dev/null
+++ b/binary_search/1300/nayoung1300.java
@@ -0,0 +1,31 @@
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+
+// 풀이 참고 : https://st-lab.tistory.com/281
+
+public class nayoung1300 {
+    public static void main(String[] args) throws IOException {
+        BufferedReader br  = new BufferedReader(new InputStreamReader(System.in));
+
+        int N = Integer.parseInt(br.readLine());
+        int k = Integer.parseInt(br.readLine());
+
+        long low = 1;
+        long high = k;
+
+        while (low < high) {
+            long mid = (low + high) / 2;
+            long count = 0;
+
+            for (int i  = 1; i <= N; i++) {
+                count += Math.min(mid / i, N);
+            }
+
+            if (k <= count) high = mid;
+            else low = mid + 1;
+        }
+
+        System.out.println(low);
+    }
+}
diff --git a/binary_search/1920/nayoung1920.java b/binary_search/1920/nayoung1920.java
new file mode 100644
index 0000000..fb8c1eb
--- /dev/null
+++ b/binary_search/1920/nayoung1920.java
@@ -0,0 +1,49 @@
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.util.Arrays;
+import java.util.StringTokenizer;
+
+public class nayoung1920 {
+    public static void main(String[] args) throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        StringTokenizer st;
+
+        int N = Integer.parseInt(br.readLine());
+        int[] A = new int[N];
+
+        st = new StringTokenizer(br.readLine());
+
+        for (int i = 0; i < N; i++) {
+            A[i] = Integer.parseInt(st.nextToken());
+        }
+
+        Arrays.sort(A);
+
+        int M = Integer.parseInt(br.readLine());
+        st = new StringTokenizer(br.readLine());
+
+        for (int i = 0; i < M; i++) {
+            int m = Integer.parseInt(st.nextToken());
+            if (isInArr(A, m)) {
+                System.out.println(1);
+            } else {
+                System.out.println(0);
+            }
+        }
+    }
+
+    public static boolean isInArr(int[] A, int m) {
+        int min = 0, max = A.length - 1;
+
+        while (min <= max) {
+            int mid = (min + max) / 2;
+
+            if (A[mid] == m) return true;
+            else if (A[mid] < m) min = mid + 1;
+            else max = mid - 1;
+        }
+
+        return false;
+    }
+}
diff --git a/binary_search/19637/nayoung19637.java b/binary_search/19637/nayoung19637.java
new file mode 100644
index 0000000..1147f8a
--- /dev/null
+++ b/binary_search/19637/nayoung19637.java
@@ -0,0 +1,56 @@
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.util.*;
+
+public class nayoung19637 {
+    public static void main(String[] args) throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+
+        StringTokenizer st = new StringTokenizer(br.readLine());
+
+        StringBuilder sb = new StringBuilder();
+
+        int N = Integer.parseInt(st.nextToken());
+        int M = Integer.parseInt(st.nextToken());
+
+        List<Item> items = new ArrayList<>();
+
+        for (int i = 0; i < N; i++) {
+            st = new StringTokenizer(br.readLine());
+            String name = st.nextToken();
+            int value = Integer.parseInt(st.nextToken());
+
+            items.add(new Item(name, value));
+        }
+
+        for (int i = 0; i < M; i++) {
+            int power = Integer.parseInt(br.readLine());
+
+            int low = 0;
+            int high = N-1;
+
+            while (low <= high) {
+                int mid = (low + high) / 2;
+
+                if (power <= items.get(mid).value) high = mid - 1;
+                else low = mid + 1;
+            }
+
+            sb.append(items.get(high+1).name).append('\n');
+        }
+
+        System.out.println(sb);
+
+    }
+
+    static class Item {
+        String name;
+        int value;
+
+        public Item(String name, int value) {
+            this.name = name;
+            this.value = value;
+        }
+    }
+}