[Probability] baekjoon-13251

Author: Seogeurim

Diff for: README.md

@@ -72,4 +72,10 @@
 | 01  |     | [Baekjoon-11050 이항 계수 1](https://github.com/Seogeurim/Algorithm-practice/blob/master/src/Combination/P11050) |      |
 | 02  |     | [Baekjoon-11051 이항 계수 2](https://github.com/Seogeurim/Algorithm-practice/blob/master/src/Combination/P11051) | DP   |
 | 03  |     | [Baekjoon-1010 다리 놓기](https://github.com/Seogeurim/Algorithm-practice/blob/master/src/Combination/P1010) | DP     |
-| 04  | ⭐️ | [Baekjoon-1256 사전](https://github.com/Seogeurim/Algorithm-practice/blob/master/src/Combination/P1256) |        |
+| 04  | ⭐️ | [Baekjoon-1256 사전](https://github.com/Seogeurim/Algorithm-practice/blob/master/src/Combination/P1256) |        |
+
+### Probability
+
+|  #  |   ☆    | Problem                                                                                                             | Note                      |
+| :-: | :----: | :------------------------------------------------------------------------------------------------------------------ | :------------------------ |
+| 01  |     | [Baekjoon-13251 조약돌 꺼내기](https://github.com/Seogeurim/Algorithm-practice/blob/master/src/Probability/P13251) |      |

Diff for: src/Probability/P13251/Main.java

@@ -0,0 +1,39 @@
+package Probability.P13251;
+
+import java.io.BufferedReader;
+import java.io.FileInputStream;
+import java.io.InputStreamReader;
+import java.util.StringTokenizer;
+
+public class Main {
+
+    static int N = 0, M, K;
+    static int[] colors;
+    static double ans = 0;
+
+    public static void main(String[] args) throws Exception {
+        System.setIn(new FileInputStream("src/Probability/P13251/input.txt"));
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+
+        M = Integer.parseInt(br.readLine());
+
+        colors = new int[M];
+        StringTokenizer st = new StringTokenizer(br.readLine());
+        for (int i = 0; i < M; i++) {
+            colors[i] = Integer.parseInt(st.nextToken());
+            N += colors[i];
+        }
+
+        K = Integer.parseInt(br.readLine());
+
+        for (int i = 0; i < M; i++) {
+            double colorPro = 1;
+            for (int j = 0; j < K; j++) {
+                colorPro *= (double) (colors[i] - j) / (N - j);
+            }
+            ans += colorPro;
+        }
+
+        System.out.println(ans);
+    }
+}

Diff for: src/Probability/P13251/input.txt

@@ -0,0 +1,3 @@
+1
+13
+8