From 35f166b614850593af8949b1b449844adc28f2c2 Mon Sep 17 00:00:00 2001
From: Kirito <1362050620@qq.com>
Date: Sat, 2 Jul 2016 12:56:38 +0800
Subject: [PATCH] Create 1125.cpp

---
 QUSTOJ/1125.cpp | 49 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 49 insertions(+)
 create mode 100644 QUSTOJ/1125.cpp

diff --git a/QUSTOJ/1125.cpp b/QUSTOJ/1125.cpp
new file mode 100644
index 0000000..2a11ca4
--- /dev/null
+++ b/QUSTOJ/1125.cpp
@@ -0,0 +1,49 @@
+#include <cstdio>
+#include <cstdlib>
+#include <vector>
+#include <algorithm>
+using namespace std;
+//Written by Coffee. 判断素数
+bool isPrime(int num)
+{
+	if (num == 2 || num == 3)
+	{
+		return true;
+	}
+	if (num % 6 != 1 && num % 6 != 5)
+	{
+		return false;
+	}
+	for (int i = 5; i*i <= num; i += 6)
+	{
+		if (num % i == 0 || num % (i+2) == 0)
+		{
+			return false;
+		}
+	}
+	return true;
+}
+
+int main()
+{
+    int n,k;
+    vector<int> vec;
+    scanf("%d %d",&n,&k);
+    int tmp;
+    for(int i=0;i<n;i++)
+    {
+        scanf("%d",&tmp);
+        vec.push_back(tmp);
+    }
+    sort(vec.begin(),vec.end());
+    int m=vec.at(n-k)-vec.at(k-1);
+    if(isPrime(m))
+    {
+        printf("YES\n");
+    }
+    else
+    {
+        printf("NO\n");
+    }
+    return printf("%d\n",m),0;
+}