From http://www.cnblogs.com/d-e-v-i-l/p/5435509.html

SDUSTOJ/1795_cnblogs.cpp

@@ -0,0 +1,53 @@
+/* ***********************************************
+Author        :devil
+Created Time  :2016/4/26 16:10:39
+************************************************ */
+#include <cstdio>
+#include <cstring>
+#include <iostream>
+#include <algorithm>
+#include <vector>
+#include <queue>
+#include <set>
+#include <map>
+#include <string>
+#include <cmath>
+#include <stdlib.h>
+using namespace std;
+typedef long long LL;
+const int N=2e6+7;
+int a[N],b[N];
+long long sum[N];
+int main()
+{
+    //freopen("in.txt","r",stdin);
+    int n,x;
+    while(~scanf("%d",&n))
+    {
+        int ma=0;
+        memset(a,0,sizeof(a));
+        memset(b,0,sizeof(b));
+        memset(sum,0,sizeof(sum));
+        for(int i=0;i<n;i++)
+        {
+            scanf("%d",&x);
+            ma=max(ma,x);
+            a[x]++;
+        }
+        for(int i=1;i<=ma*2+1;i++)
+        {
+            sum[i]=sum[i-1]+a[i]*i;
+            b[i]=b[i-1]+a[i];
+        }
+        LL ans=1e12+10;
+        for(int i=1;i<=ma;i++)
+        {
+            LL now=sum[i-1];
+            for(int j=1;i*j<=ma;j++)
+                now=now+(b[i*(j+1)-1]-b[i*j-1])*j+sum[i*(j+1)-1]-sum[i*j]-(b[i*(j+1)-1]-b[i*j])*j*i;
+            ans=min(ans,now);
+        }
+        printf("%lld\n",ans);
+    }
+    return 0;
+}