Go: // n×nの成長度表に現れる数字を重複を許してm-1個選んで掛け合わせる時の最大値を求める
// ->掛け算型のDP

package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
	"strings"
)

var scanner = bufio.NewScanner(os.Stdin)

func main() {
	for scanner.Scan() {
		buf := strings.Split(scanner.Text(), " ")
		n, _ := strconv.Atoi(buf[0])
		m, _ := strconv.Atoi(buf[1])
		if n == 0 && m == 0 {
			break
		}
		growth_table := make([][]float64, n)
		for i := range growth_table {
			scanner.Scan()
			buf_ := strings.Split(scanner.Text(), " ")
			tmp := make([]float64, n)
			for j := range tmp {
				tmp[j], _ = strconv.ParseFloat(buf_[j], 64)
			}
			growth_table[i] = tmp
		}
		dp := make([][]float64, m)
		for i := range dp {
			dp[i] = make([]float64, n)
		}
		for i := range dp {
			dp[0][i] = 1
		}
		for k := 1; k < m; k++ {
			// k個使うとき...
			for i := 0; i < n; i++ {
				for j := 0; j < n; j++ {
					// 新たにgrowth_table[i][jを使うかどうか
					dp[k][j] = max(dp[k][j], dp[k-1][i]*growth_table[i][j])
					// check(dp)
				}
			}
		}
		ans := 0.0
		for i := 0; i < n; i++ {
			if dp[m-1][i] > ans {
				ans = dp[m-1][i]
			}
		}
		fmt.Printf("%.2f\n", ans)
	}
}

func max(a, b float64) float64 {
	if a < b {
		return b
	}
	return a
}

// func check(dp [][]float64) {
// 	log.Println()
// 	for i := range dp {
// 		log.Println(dp[i])
// 	}
// 	log.Println()
// }

C++: #include <vector>
#include <map>
#include <set>
#include <stack>
#include <queue>
#include <algorithm>
#include <numeric>
#include <utility>
#include <sstream>
#include <iostream>
#include <iomanip>
#include <cstdio>
#include <cmath>
#include <string>
#include <cstring>
#include <complex>
#include <ctime>
#include <cstdlib>

using namespace std;

inline int to_int(string s) {int v; istringstream sin(s); sin >> v; return v;}
template<class T> inline string to_str(T x) {ostringstream sout; sout << x; return sout.str();}

typedef long long ll;
const int INF = 1 << 30;

int main()
{
	double T[128][128], dp[128][128];
	int n, m;

	while(cin >> n >> m)
	{
		if(n == 0 && m == 0)
		{
			break;
		}

		for(int i = 0; i < n; i++)
		{
			for(int j = 0; j < n; j++)
			{
				cin >> T[i][j];
			}
		}
		
		memset(dp, 0, sizeof(dp));
	
		for(int i = 0; i < n; i++)
		{
			dp[0][i] = 1.0;
		}

		for(int i = 1; i < m; i++)
		{
			for(int j = 0; j < n; j++)
			{
				for(int k = 0; k < n; k++)
				{
					//dp[i][j] : i回目で肥料kを使った時の最大の苗木の大きさ
					dp[i][j] = max(dp[i][j], dp[i-1][k]*T[k][j]);
				}
			}
		}

		double res = 0; 
		for(int i = 0; i < n; i++)
		{
			res = max(res, dp[m-1][i]);
		}
	
		res *= 100;
		res = int(res+0.5);
		res /= 100;

		printf("%.2f\n",res);
	}
}

C++: #include <iostream>
#include <string>
#include <cstdio>
#include <vector>
#include <algorithm>
#include <cmath>
#include <cstdlib>
using namespace std;

#define rep(i,a) for(int i = 0 ; i < a ; i ++)
#define loop(i,a,b) for(int i = a ; i < b ; i ++)

double dt[102][102];
double dp[102][102];
int n;

double dfs(int d,int v){
	if(abs(dp[d][v]+1)>1e-6)return dp[d][v];
	if(d == 0) return 1.0;
	double r=-1;
	for(int i = 0 ; i < n ; i++){
		r = max(r,dfs(d-1,i) * dt[i][v]);
	}

	return dp[d][v] = r;
}

int main(void){
	int m;
	while(cin>>n>>m,n+m){

		rep(i,n)
			rep(j,n)cin>>dt[i][j];
		rep(i,102)rep(j,102)dp[i][j] = -1;
		
		//rep(i,n)rep(j,n)cout<<dt[i][j]<<(j==n-1?'\n':' ');


		double r = 0;
		rep(i,n){
			r = max(r,dfs(m-1,i));
		}
		printf("%lf\n",r);
	}
}

C++: #include <iostream>
#include <vector>
#include <stack>
#include <queue>
#include <map>
#include <bitset>
#include <algorithm>
#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <cstring>
using namespace std;
double key[100][100];
double table[100][100];

void Init(int n, int m){
	for(int i = 0; i < n; i++) for(int j = 0; j < m; j++) table[i][j] = 0;
}

double memo(int cur, int count, int limit, int kind){
	if(table[cur][count]) return table[cur][count];
	if(count==limit) return 1.0;
	for(int i = 0; i < kind; i++) table[cur][count] = max(table[cur][count], memo(i, count+1, limit, kind)*key[i][cur]);
	return table[cur][count];
}

int main(){
	int n, m;
	while(cin >> n >> m && ((n!=0)||(m!=0))){
		Init(n, m);
		for(int i = 0; i < n; i++) for(int j = 0; j < n; j++) cin >> key[i][j];
		for(int i = 0; i < n; i++) table[i][0] = memo(i, 0, m-1, n);
		double max = 0;
		for(int i = 0; i < n; i++) if(max < table[i][0]) max = table[i][0];
		printf("%0.2f\n", max);
	}

	return 0;
}

C++: #include <iostream>
#include <vector>
#include <stack>
#include <queue>
#include <map>
#include <bitset>
#include <algorithm>
#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <cstring>
using namespace std;
double key[100][100];
double table[100][100];

void Init(int n, int m){
	for(int i = 0; i < n; i++) for(int j = 0; j < m; j++) table[i][j] = 0;
}

double memo(int cur, int count, int limit, int kind){
	if(table[cur][count]) return table[cur][count];
	if(count==limit) return 1.0;
	double Max = 0;
	int prev = 0;
	for(int i = 0; i < kind; i++){
		double tmp = memo(i, count+1, limit, kind);
		if(Max <= tmp){
			if(Max*key[prev][cur] < tmp*key[i][cur]){
				Max = tmp;
				prev = i;
			}
		}
	}
	table[cur][count] = Max*key[prev][cur];
	return table[cur][count];
}

int main(){
	int n, m;
	while(cin >> n >> m && ((n!=0)||(m!=0))){
		Init(n, m);
		for(int i = 0; i < n; i++) for(int j = 0; j < n; j++) cin >> key[i][j];
		for(int i = 0; i < n; i++) table[i][0] = memo(i, 0, m-1, n);
		double max = 0;
		for(int i = 0; i < n; i++) if(max < table[i][0]) max = table[i][0];
		printf("%0.2f\n", max);
	}

	return 0;
}

C++: #include<iostream>
#include<string>
#include<cstdlib>
#include<cmath>
#include<algorithm>

using namespace std;

int main() {
	while(1) {
		int n, m;
		cin >> n >> m;
		if(n == 0 && m == 0) break;
		double data[n][n];
		for(int i=0; i<n; i++) {
			for(int j=0; j<n; j++) {
				cin >> data[i][j];
			}
		}

		double dp[n][m];
		for(int i=0; i<n; i++)
			dp[i][0] = 1;

		for(int i=1; i<m; i++) {
			for(int j=0; j<n; j++) {
				double max = 0;
				for(int k=0; k<n; k++) {
					double value = dp[k][i-1] * data[k][j];
					if(value > max) max = value;
				}
				dp[j][i] = max;
			}
		}

		double ans = 0;
		for(int i=0; i<n; i++) {
			if(ans < dp[i][m-1]) ans = dp[i][m-1];
		}
		cout << ans << endl;
	}
	return 0;
}

C++: #include <vector>
#include <map>
#include <set>
#include <stack>
#include <queue>
#include <algorithm>
#include <numeric>
#include <utility>
#include <sstream>
#include <iostream>
#include <iomanip>
#include <cstdio>
#include <cmath>
#include <string>
#include <cstring>
#include <complex>
#include <ctime>
#include <cstdlib>

using namespace std;

inline int to_int(string s) {int v; istringstream sin(s); sin >> v; return v;}
template<class T> inline string to_str(T x) {ostringstream sout; sout << x; return sout.str();}

typedef long long ll;
const int INF = 1 << 30;

int main()
{
	long double T[128][128], dp[128][128];
	int n, m;

	while(cin >> n >> m)
	{
		if(n == 0 && m == 0)
		{
			break;
		}

		for(int i = 0; i < n; i++)
		{
			for(int j = 0; j < n; j++)
			{
				cin >> T[i][j];
			}
		}
		
		memset(dp, 0, sizeof(dp));
	
		for(int i = 0; i < n; i++)
		{
			dp[0][i] = 1.0;
		}

		for(int i = 1; i < m; i++)
		{
			for(int j = 0; j < n; j++)
			{
				//dp[i][j] = -1.0;
				for(int k = 0; k < n; k++)
				{
					//dp[i][j] : i回目で肥料jを使った時の最大の苗木の大きさ
					dp[i][j] = max(dp[i][j], dp[i-1][k]*T[k][j]);
				}
			}
		}

		long double res = -1; 
		for(int i = 0; i < n; i++)
		{
			res = max(res, dp[m-1][i]);
		}
	
		printf("%.2Lf\n",res);
	}
}