Revise paste b1d29f0f98928

#include <iostream>
#include <set>
using namespace std;
const int maxn=200005;
int n,a[maxn];
 
long long segment_tree[3*maxn];
 
long long merge_nodes(long long A, long long B){
  return A^B;
}
 
void build_tree(int L=0,int R=n-1,int node=1){
  if(L==R){
    segment_tree[node]=a[L];
  }else{
    int middle=(L+R)/2;
    build_tree(L,middle,2*node);
    build_tree(middle+1,R,2*node+1);
    segment_tree[node]=merge_nodes(segment_tree[2*node],segment_tree[2*node+1]);
  }
}
 
long long query(int i,int j,int L=0,int R=n-1,int node=1){
  if(R<i || j<L){
    return 0;
  }
  if(i<=L && R<=j){
    return segment_tree[node];
  }
  int middle=(L+R)/2;
  long long left=query(i,j, L, middle,2*node);
  long long right=query(i,j,middle + 1, R,2*node+1);
  return merge_nodes(left,right);
}
 
int main()
{
    int q;
    cin>>n>>q;
    for(int i = 0;i<n;i++){
        cin>>a[i];
    }
    build_tree();
 
    for(int i=0;i<q;i++){
        int A,B;
        cin>>A>>B;
        cout<<query(A-1,B-1)<<endl;
    }
    return 0;
}