HDU 5875 Function

#pragma comment(linker, "/STACK:1024000000,1024000000")
#include<cstdio>
#include<cstring>
#include<cmath>
#include<algorithm>
#include<vector>
#include<map>
#include<set>
#include<queue>
#include<stack>
#include<iostream>
using namespace std;
typedef long long LL;
const double pi=acos(-1.0),eps=1e-6;
void File()
{
freopen("D:\\in.txt","r",stdin);
freopen("D:\\out.txt","w",stdout);
}
template <class T>
inline void read(T &x)
{
char c=getchar(); x=0;
while(!isdigit(c)) c=getchar();
while(isdigit(c)) {x=x*10+c-'0'; c=getchar();}
}

const int maxn=100010;
int T,n,Q,a[maxn],s[4*maxn],res,pos;

void build(int l,int r,int rt)
{
if(l==r) { s[rt]=a[l];return; }
int m=(l+r)/2; build(l,m,2*rt); build(m+1,r,2*rt+1);
s[rt]=min(s[2*rt],s[2*rt+1]);
}

void force(int l,int r,int rt,int num)
{
if(l==r) { pos=l; res=a[l]; return; }
int m=(l+r)/2;
if(s[2*rt]<=num) force(l,m,2*rt,num); if(res!=-1) return;
else force(m+1,r,2*rt+1,num); if(res!=-1) return;
}

void get(int L,int R,int num,int l,int r,int rt)
{
if(L<=l&&r<=R)
{
if(s[rt]>num) return;
force(l,r,rt,num); return;
}
int m=(l+r)/2;
if(L<=m) get(L,R,num,l,m,2*rt); if(res!=-1) return;
if(R>m) get(L,R,num,m+1,r,2*rt+1); if(res!=-1) return;
}

int main()
{
scanf("%d",&T);
while(T--)
{
scanf("%d",&n);
for(int i=1;i<=n;i++) scanf("%d",&a[i]);
build(1,n,1);
scanf("%d",&Q);
for(int i=1;i<=Q;i++)
{
int L,R; scanf("%d%d",&L,&R);

int ans=a[L]; pos=L;
while(1)
{
if(ans==0||pos==R) break;
res=-1; get(pos+1,R,ans,1,n,1);
if(res==-1) break; ans=ans%res;
}
printf("%d\n",ans);
}
}
return 0;
}