Submission #74714041

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Source Code Expand

#include<bits/stdc++.h>
// #include<atcoder/all>
using namespace std;
using ll = long long;
#define rep(i, n) for(int  i = 0; i < (n); ++i)
template<typename T> bool chmin(T& a, T b){if(a > b){a = b; return true;} return false;}
template<typename T> bool chmax(T& a, T b){if(a < b){a = b; return true;} return false;}
const long long INF = 1LL << 60;
using Graph = vector<vector<int>>;
int gcd(int a, int b){
    if(b == 0) return a;  
    else return gcd(b, a%b);
}
struct Compare {
    bool operator()(const pair<ll, int>& a, const pair<ll, int>& b) {
        return a.first > b.first;  
    }
};

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr); 
    int t; cin >> t;
    while(t--){
        int n; cin >> n;
        vector<int> ans(n);
        rep(i,n) ans[i] = i+1;
        if(n <= 3){
            if(n == 3){
                swap(ans[1], ans[2]);
            }
        }else{
            swap(ans[1], ans[2]);
            bool change = false;
            for(int i = 3;i<n;i+=2){
                if(i+1>=n) break;
                if(change){
                    swap(ans[i], ans[i+1]);
                    change = !change;
                }else{
                    change = !change;
                }
            }
        }
        rep(i,n){
            cout << ans[i] << " ";
        }
        cout << "\n";
    }
}

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