#include <bits/stdc++.h>
#define INF 1000000000000000000
#define print2d(arr) for(auto x: arr) { for(auto y: x) cout << y << " "; cout <<"\n";}
#define print1d(arr) for(auto x: arr) {cout << x << " ";} cout << "\n";

using namespace std;
int binomialCoeffUtil(int n, int k, vector<vector<int>> &dp) { 
    if (dp[n][k] != -1)      
        return dp[n][k]; 
    else if (k == 0 || k == n) { 
        dp[n][k] = 1; 
        return dp[n][k]; 
    }
      
    dp[n][k] = binomialCoeffUtil(n - 1, k - 1, dp) + binomialCoeffUtil(n - 1, k, dp); 
    return dp[n][k];
}

int binomialCoeff(int n, int k) {
    if (k > n)
      return 0;

    vector<vector<int>> dp(n+1, vector<int> (k+1, -1));   
    return binomialCoeffUtil(n, k, dp); 
}

int power_mod_p(int a, int b, int p) {
    if (a==0)
        return 0;
    int res = 1;
    a%=p;
    while (b>0) {
        if (b&1) {
            res=(res*a)%p;
            b>>=1;
            a=(a*a)%p;
        }
    }
        return res;
}

// lower_bound => first element having value not less than val
// upper_bound => first element having value greater than val
// in an ascending sorted array


typedef long long ll;
typedef unsigned long long ull;

bool comp(pair<int, pair<int, int>> a, pair<int, pair<int, int>> b) {
	return (a.first < b.first);
}

int main() {
   ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL); 

   int t;
   cin >> t;

   while (t--) {
   	int n, m;
   	cin >> n >> m;

   	vector<vector<int>> arr(n, vector<int> (m));
   	vector<pair<int, pair<int, int>>> tmp;

   	for (int i =0;i < n; i++) {
   		for (int j =0; j < m; j++) {
   			cin >> arr[i][j];
   		

   			tmp.push_back(make_pair(arr[i][j], make_pair(i, j)));
   		}
   	}

   	sort(tmp.begin(), tmp.end(), comp);
   	for (int i =0;i < n; i++) {
   		sort(arr[i].begin(), arr[i].end());
   	}

   	vector<pair<int, int>> idx(n);
   	for (int i =0;i < n; i++) {
   		idx[i].first = 0;
   		idx[i].second = m-1;
   	}
   	/*
   	for (int i =0; i < m; i++) {
   		cout << tmp[i].first << " " << tmp[i].second.first << " " << tmp[i].second.second << "\n";
   	}*/

   	vector<int> sml(m);
   	vector<vector<int>> ans(n, vector<int> (m));
   	for (int i = 0; i < m; i++) {
   		pair<int, pair<int, int>> curr = tmp[i];
   		ans[tmp[i].second.first][i] = curr.first;

   		for (int j = 0; j < n;j++) {
   			if (ans[j][i] == 0) {
   				ans[j][i] = arr[j][idx[j].second];
   				idx[j].second--;
   			}
   		}
   	}

   	print2d(ans);
   }

}