HDU 4928 Series 2

#include <iostream>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <cmath>
#include <algorithm>
#include <string>
#include <queue>
#include <stack>
#include <vector>
#include <map>
#include <set>
#include <functional>
#include <time.h>

using namespace std;

typedef __int64 ll;

const int INF = 1<<30;
const int MAXN = (int) 1e5+55;

ll a[MAXN];
int n;

inline int check(ll A[], int len) {
    bool INC = true, DEC = true;
    for (int i = 0; i < len-1; i++)
        if (A[i+1]>A[i]) INC = false;
        else if (A[i+1]<A[i]) DEC = false;
    return INC||DEC;
}

int solve() {
    int cur = 0;
    int l = 0, r = n-1;
    for (int i = 0; i < n; i++) {
        while (l<r && a[l]==0) l++;
        while (l<r && a[r]==0) r--;
        l = max(0, l-1);
        r = min(r+1, n-i);

        if (!check(a+l, r-l)) return i;

        for (int j = l; j < r; j++)
            a[j] = a[j+1]-a[j];
        r--;
    }
    return n;
}

int main() {
    #ifdef Phantom01
        freopen("HDU4928.txt", "r", stdin);
    #endif //Phantom01

    int T;
    scanf("%d", &T);
    while (T--) {
        scanf("%d", &n);
        for (int i = 0; i < n; i++)
            scanf("%I64d", &a[i]);
        int ans = solve();
        if (0==ans) puts("ugly series");
        else if (n==ans) puts("nice series");
        else printf("%d\n", ans-1);
    }

    return 0;
}