segment tree minimum query

#include <iostream>
#define mx 100001

int arr[mx], tree[mx*3];
using namespace std;
int query( int node , int b, int e, int i,  int j)
{
    if(i>e || j<b)
    {
        return mx;
    }
    else if(b>=i && e<=j)
    {
        return tree[node];
    }
    else
    {
     int mid=(b+e)/2;
        int left =node*2;
        int right=node*2+1;
        int la=query(left,b,mid,i,j);
        int ra=query(right,mid+1,e,i,j);
        return min(la,ra);
    }
}

void init( int node, int b, int e)
{
    if(b==e)

    {
        tree[node]=arr[b];

        return ;
    }
    int mid=(b+e)/2;
    int left=node*2;
    int right =node*2+1;
    init(left,b,mid);
    init(right,mid+1,e);
    tree[node]=tree[left]+tree[right];
}

int main()
{
    int n,i,t,p,j,n1,n2,k;
    cin>>t;
    for(i=1;i<=t;i++)
    {
        cin>>n;
        cin>>p;
        for(k=1;k<=n;k++)
        {
            cin>>arr[i];
        }
        init(1,1,n);
        for(j=1;j<=p;j++)
        {    cin>>n1>>n2;
            cout<<query(1,1,n,n1,n2)<<endl;
        }


    }

}