diff --git a/HDOJ/1166.cpp b/HDOJ/1166.cpp
new file mode 100644
index 0000000..33f2e73
--- /dev/null
+++ b/HDOJ/1166.cpp
@@ -0,0 +1,92 @@
+#include <cstdio>
+#include <cstdlib>
+#include <cstring>
+using namespace std;
+
+
+int C[131072];
+
+char cmd[32];
+
+int getsum(int left,int right,int pos,int leftbound,int rightbound)
+{
+    if(left<=leftbound&&right>=rightbound)
+    {
+        return C[pos];
+    }
+    if(right<leftbound||left>rightbound)
+    {
+        return 0;
+    }
+    int a=getsum(left,right,2*pos+1,leftbound,(leftbound+rightbound)/2);
+    int b=getsum(left,right,2*pos+2,(leftbound+rightbound)/2+1,rightbound);
+    return a+b;
+}
+int main()
+{
+    int t;
+    scanf("%d",&t);
+    for(int itt=1;itt<=t;itt++)
+    {
+        printf("Case %d:\n",itt);
+        int N;
+        scanf("%d",&N);
+        int realn=1;
+        while(realn<N)
+        {
+            realn*=2;
+        }
+        memset(C,0,sizeof(int)*realn);
+        for(int i=0;i<N;i++)
+        {
+            scanf("%d",&C[realn-1+i]);
+        }
+        int start=(realn-1)/2;
+        while(start>0)
+        {
+            int L=start+1;
+            for(int i=0;i<L;i++)
+            {
+                C[start+i]=C[2*(start+i)+1]+C[2*(start+i)+2];
+            }
+            start=(start-1)/2;
+        }
+        C[0]=C[1]+C[2];
+        while(scanf("%s",cmd)==1)
+        {
+            if(strcmp(cmd,"End")==0)
+            {
+                break;
+            }
+            int a,b;
+            scanf("%d %d",&a,&b);
+            if(strcmp(cmd,"Query")==0)
+            {
+                int ans=getsum(a-1,b-1,0,0,realn-1);
+                printf("%d\n",ans);
+            }
+            else if(strcmp(cmd,"Add")==0)
+            {
+                int pos=realn-1+a-1;
+                while(pos>0)
+                {
+                    C[pos]+=b;
+                    pos=(pos-1)/2;
+                }
+                C[0]+=b;
+            }
+            else if(strcmp(cmd,"Sub")==0)
+            {
+                int pos=realn-1+a-1;
+                while(pos>0)
+                {
+                    C[pos]-=b;
+                    pos=(pos-1)/2;
+                }
+                C[0]-=b;
+            }
+        }
+    }/// end of for(...)
+
+    return 0;
+}