HDU 5875 H - Function 用单调栈水过了

#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <algorithm>
#define IOS ios::sync_with_stdio(false)
using namespace std;
#define inf (0x3f3f3f3f)
typedef long long int LL;

#include <iostream>
#include <sstream>
#include <vector>
#include <set>
#include <map>
#include <queue>
#include <string>
const int maxn = 1e5 + 20;
int a[maxn];
int to[maxn];
struct node {
    int id;
    int val;
}stack[maxn];
void work() {
    int n;
    scanf("%d", &n);
    for (int i = 1; i <= n; ++i) {
        scanf("%d", &a[i]);
    }
    int top = 1;
    a[n + 1] = -1;
    stack[top].val = a[1];
    stack[top].id = 1;
    for (int i = 2; i <= n + 1; ++i) {
        while (top >= 1 && a[i] <= stack[top].val) {
            to[stack[top].id] = i;
            top--;
        }
        ++top;
        stack[top].val = a[i];
        stack[top].id = i;
    }
//    for (int i = 1; i <= n; ++i) {
//        printf("%d ", to[i]);
//    }
//    printf("\n");
    int m;
    scanf("%d", &m);
    for (int i = 1; i <= m; ++i) {
        int L, R;
        scanf("%d%d", &L, &R);
        int ans = a[L];
        int t = to[L];
        while (t <= R) {
            ans %= a[t];
            if (ans == 0) break;
            t = to[t];
        }
        printf("%d\n", ans);
    }
}

int main() {
#ifdef local
    freopen("data.txt","r",stdin);
#endif
    int t;
    scanf("%d", &t);
    while (t--) work();
    return 0;
}