diff --git a/C++/create_segment_tree.cpp b/C++/create_segment_tree.cpp
new file mode 100644
index 00000000..0812c6f3
--- /dev/null
+++ b/C++/create_segment_tree.cpp
@@ -0,0 +1,148 @@
+/*
+segment tree
+You have given an array A of n elements. Your task is to process q queries of the following types.
+1 i x : Update the value at position i to x.
+2 i j : Print the sum of values in the range [i, j].
+*/
+
+#include<bits/stdc++.h>
+using namespace std;                                                                                                                                          
+typedef long long int ll;                             //g++ ll.cpp -o ll.exe
+typedef long double ld;  
+typedef pair<ll,ll> iii;                              //all elements to 0
+const ll mod =1e9+7;
+
+
+
+struct node
+{
+  ll x;
+
+};
+
+
+vector<node> g;
+vector<ll> ar;
+
+node merge(node a,node b)
+{
+  node temp;
+  temp.x=a.x+b.x;
+  return temp;
+}
+
+void build(ll index,ll l,ll r)
+{
+
+  if(l==r)
+  {
+    node tt;
+    tt.x=ar[l];
+    g[index]=tt;
+    return;
+  }
+
+  ll mid;
+  mid=(l+r)/2;
+  build(2*index,l,mid);
+  build(2*index+1,mid+1,r);
+  g[index]=merge(g[2*index],g[2*index+1]);
+}
+
+void update(ll index,ll l,ll r,ll pos,ll value)
+{
+
+  if((pos<l)|| (pos>r))
+  return; 
+
+
+  if(l==r)
+  {
+    //cout<<index<<endl;
+    node tt;
+    tt.x=value;
+    g[index]=tt;
+    ar[l]=value;
+    return;
+  }
+
+  ll mid;
+  mid=(l+r)/2;
+  update(2*index,l,mid,pos,value);
+  update(2*index+1,mid+1,r,pos,value);
+  g[index]=merge(g[2*index],g[2*index+1]);
+
+
+}
+
+
+ node query(ll index,ll l,ll r,ll lq,ll rq)
+ {
+  node ans;
+  ans.x=0;
+
+  if(lq> r || rq<l)
+    return ans;
+
+  if(lq<=l && rq>=r)
+    return(g[index]);
+
+  ll mid=(l+r)/2;
+  ans=merge(query(2*index,l,mid,lq,rq),query(2*index+1,mid+1,r,lq,rq));
+
+  return(ans);
+
+
+
+ }
+
+
+int main()
+{
+    #ifndef ONLINE_JUDGE
+    freopen("input.txt", "r", stdin);
+    freopen("output.txt", "w", stdout);
+    #endif
+    ios_base::sync_with_stdio(0);
+    cin.tie(0); cout.tie(0);
+
+  ll n,q;
+  cin>>n>>q;
+
+  g.resize(4*n+6);
+  ar.resize(n+1);
+
+  for(ll i=1;i<=n;i++)
+    cin>>ar[i];
+
+  build(1,1,n);
+
+  while(q--)
+  {
+    ll t;
+    cin>>t;
+    if(t==1)
+    {
+      ll i,x;
+      cin>>i>>x;
+      update(1,1,n,i,x);
+    }
+    if(t==2)
+    {
+      ll lq,rq;
+      cin>>lq>>rq;
+      node temp;
+      temp=query(1,1,n,lq,rq);
+      cout<<temp.x<<endl;
+
+    }
+  }
+
+
+
+
+
+
+
+    return 0;
+}