POJ 2470

#include<iostream>
#include<stdio.h>
#include<vector>
using namespace std;

int main()
{
    //freopen("acm.acm","r",stdin);
    vector<int> coll;
    int num;
    int a;
    int i;
    bool * boo;
    while(1)
    {
    scanf("%d",&num);
    if(num == 0)
        break;
    boo = new bool[num];
    memset(boo,false,sizeof(bool)*num);
    for(i = 0; i < num; ++ i)
    {
        scanf("%d",&a);
        coll.push_back(a);
    }
    for(i = 0; i < num; ++ i)
    {
        if(boo[i])
        {
            continue;            
        }
        else
        {
        if(coll[coll[i] - 1] != i +1)
        {
            cout<<"not ambiguous"<<endl;
            break;
        }
        else
        {
            boo[coll[i] - 1] = true;
            //boo[i] = true;
        }

        }

    }
    if(i == num)
    {
        cout<<"ambiguous"<<endl;
    }
    delete[] boo;
    coll.clear();
    }
}