백준/골드: 11050 이항 계수 1 문제풀이 (#23)

src/baekjoon/step/combinatoric/PROB11050.java

@@ -0,0 +1,30 @@
+package baekjoon.step.combinatoric;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.util.StringTokenizer;
+
+public class PROB11050 {
+    // nCr = r! / n!(n - r)!
+
+    static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+    static StringTokenizer st;
+    static int a, b;
+
+    public static void main(String[] args) throws IOException {
+        st = new StringTokenizer(br.readLine());
+        a = Integer.parseInt(st.nextToken());
+        b = Integer.parseInt(st.nextToken());
+
+        System.out.println(fac(a) / (fac(b) * fac(a - b)));
+    }
+
+    public static int fac (int n) {
+        if (n == 0) {
+            return 1;
+        }
+
+        return n * fac(n - 1);
+    }
+}