1523C - Compression and Expansion - CodeForces Solution

//      BISMILLAH-IR-RAHMAN-IR-RAHIM
 
 
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef unsigned long long ull;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef vector<vi> vvi;
typedef vector<vl> vvl;
typedef pair<int, int> pii;
typedef pair<float, float> pff;
typedef pair<double, double> pdd;
typedef pair<ll, ll> pll;
#define el << '\n'
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds ;
template <class T>
using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update> ;
#define pb push_back
#define PI 3.14159265358979323
#define file() freopen("input.txt", "r", stdin); freopen("output.txt", "w", stdout)
#define fastIO	ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0) ;
ll bin_expo(ll base, ll pow, ll m) {
        if (pow == 0) return 1;
        ll ret = bin_expo(base, pow / 2, m) % m;
        if (pow & 1) return (ret % m * ret % m * base % m) % m;
        else return (ret % m * ret % m) % m;
}
ll mod_add(ll a, ll b, ll m) { return ((a % m) + (b % m)) % m; }
ll mod_sub(ll a, ll b, ll m) { return ((a % m) - (b % m)) % m; }
ll mod_mul(ll a, ll b, ll m) { return ((a % m) * (b % m)) % m; }
ll mod_div(ll a, ll b, ll m) { return ((a % m) * bin_expo(b, m - 2, m)) % m; }
ll lcm(ll a, ll b) { return (a * b) / __gcd(a, b); }
int dx[] = {0, 0, +1, -1, +1, -1, -1, +1};
int dy[] = {+1, -1, 0, 0, +1, -1, +1, -1};
const ll infLL = 4e18 + 123;
const ll inf = 1e17 + 7;
const ll mod = 1e9 + 7;
const ll mod2 = 1e9 + 9;
const int mx = 2e5 + 123;
const double eps = 1e-7;
 
 
// forever-striver 
 
 
void solution() { 
 
        ll n ; 
        cin >> n  ; 
        stack<ll>stk ; 
        for(ll i=0;i<n;i++) {
                ll x ; 
                cin >> x ; 
                stack<ll>tmp; 
                tmp = stk ; 
                vl v ; 
                if(x==1) {
                        stk.push(1) ; 
                        tmp.push(1) ; 
                        while(!tmp.empty()) {
                                v.push_back(tmp.top()) ; 
                                tmp.pop() ; 
                        } 
                }
                else {
                        while(!tmp.empty() and tmp.top()!=(x-1)) {
                                //v.push_back(tmp.top()) ; 
                                tmp.pop() ; 
                        }
                        v.push_back(x) ; 
                        if(!tmp.empty()) {
                                tmp.pop() ; 
                                while(!tmp.empty()) {
                                        v.push_back(tmp.top()) ; 
                                        tmp.pop() ; 
                                }
                        }
                }
                reverse(v.begin(),v.end()) ; 
                for(int j=0;j<v.size();j++) {
                        if(j<v.size()-1) {
                                cout << v[j] << "." ; 
                        }
                        else cout << v[j] el ; 
                }
                reverse(v.begin(),v.end()) ;
                stack<ll>newstk ; 
                while(v.size()) {
                        newstk.push(v.back()) ; 
                        v.pop_back() ; 
                }
                stk = newstk ; 
        }
 
}
 
 
int main() {
        fastIO;
        // file() ;
        ll _ = 1; cin >> _;
        while (_--) solution();
        return 0 ;
}