1713C - Build Permutation - CodeForces Solution

#include <bits/stdc++.h>

using namespace std;

#define mp make_pair
#define pb push_back
#define int long long
#define pii pair<int, int>
#define fi first
#define se second
#define all(v) v.begin(), v.end()

#define trace(x) cout << '>' << #x << ':' << x << "\n"
#define trace2(x,y) cout<< '>' << #x << ':' << x << " | " << #y << ':' << y << "\n"
#define trace3(a,b,c) cout<<#a<<"="<<(a)<<", "<<#b<<"="<<(b)<<", "<<#c<<"="<<(c)<<"\n"
#define trace4(a,b,c,d) cout<<#a<<"="<<(a)<<", "<<#b<<"="<<(b)<<", "<<#c<<"="<<(c)<<", "<<#d<<"="<<(d)<<"\n"

template <typename T>
void print(T var){
    cout << var << ' ';
    return;
}

template <typename T>
void print(vector <T> var){
    for (auto x: var)
        print(x);
    cout << "\n";
    return;
}

int dx[4] = {-1, 0, 1, 0};
int dy[4] = {0, -1, 0, 1};
const int mod = 1e9+7;

bool sq(int x) {
    int xx = sqrt(x);
    return (xx*xx==x);
}

signed main(){

    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);

    int t;
    cin >> t;

    while (t--) {
        int n;
        cin >> n;
        vector<int> v(n);
        iota(all(v),0);
        for (int i = n-1; i >= 0; i--) {
            for (int j = i; j >= 0; j--) {
                if (sq(i+j)) {
                    reverse(v.begin()+j, v.begin()+i+1);
                    i = j;
                    break;
                }
            }
        }
        for (int i: v) cout << i << ' ';
        cout << '\n';
    }

}