Go: // Warshall–Floyd Algorithm

package main

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

var scanner = bufio.NewScanner(os.Stdin)

const INF = 2000000000

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
		}
		c_matrix := make([][]int, m)
		for i := range c_matrix {
			c_matrix[i] = make([]int, m)
		}
		t_matrix := make([][]int, m)
		for i := range t_matrix {
			t_matrix[i] = make([]int, m)
		}
		for i := 0; i < n; i++ {
			scanner.Scan()
			buf_ := strings.Split(scanner.Text(), " ")
			a, _ := strconv.Atoi(buf_[0])
			b, _ := strconv.Atoi(buf_[1])
			c, _ := strconv.Atoi(buf_[2])
			t, _ := strconv.Atoi(buf_[3])
			c_matrix[a-1][b-1] = c
			c_matrix[b-1][a-1] = c
			t_matrix[a-1][b-1] = t
			t_matrix[b-1][a-1] = t
		}
		c_dist := make([][]int, m)
		c_prev := make([][]int, m)
		t_dist := make([][]int, m)
		t_prev := make([][]int, m)
		for i := 0; i < m; i++ {
			c_dist[i] = make([]int, m)
			c_prev[i] = make([]int, m)
			t_dist[i] = make([]int, m)
			t_prev[i] = make([]int, m)
		}
		for i := 0; i < m; i++ {
			for j := 0; j < m; j++ {
				if c_matrix[i][j] == 0 {
					c_dist[i][j] = INF
					c_prev[i][j] = -1
				} else {
					c_dist[i][j] = c_matrix[i][j]
					c_prev[i][j] = i
				}
				if t_matrix[i][j] == 0 {
					t_dist[i][j] = INF
					t_prev[i][j] = -1
				} else {
					t_dist[i][j] = t_matrix[i][j]
					t_prev[i][j] = i
				}
			}
			c_dist[i][i] = 0
			t_dist[i][i] = 0
		}
		for k := 0; k < m; k++ {
			for i := 0; i < m; i++ {
				for j := 0; j < m; j++ {
					c_newlen := c_dist[i][k] + c_dist[k][j]
					if c_newlen < c_dist[i][j] {
						c_dist[i][j] = c_newlen
						c_prev[i][j] = c_prev[k][j]
					}
				}
			}
		}
		for k := 0; k < m; k++ {
			for i := 0; i < m; i++ {
				for j := 0; j < m; j++ {
					t_newlen := t_dist[i][k] + t_dist[k][j]
					if t_newlen < t_dist[i][j] {
						t_dist[i][j] = t_newlen
						t_prev[i][j] = t_prev[k][j]
					}

				}
			}
		}
		scanner.Scan()
		k, _ := strconv.Atoi(scanner.Text())
		for i := 0; i < k; i++ {
			scanner.Scan()
			buf_ := strings.Split(scanner.Text(), " ")
			p, _ := strconv.Atoi(buf_[0])
			q, _ := strconv.Atoi(buf_[1])
			r, _ := strconv.Atoi(buf_[2])
			switch r {
			case 0:
				fmt.Println(c_dist[p-1][q-1])
			case 1:
				fmt.Println(t_dist[p-1][q-1])
			}
		}
	}
}

C++: #include <iostream>
#include <algorithm>
#define INF 1000000000
using namespace std;

int cost[2][101][101];

int n,m;

void warshall_floyd(){
  for(int i = 0 ; i < m ; i++ ){
    for(int j = 0 ; j < m ; j++ ){
      for(int k = 0 ; k < m ; k++ ){
	cost[0][i][j] = min(cost[0][i][j],cost[0][i][k] + cost[0][k][j]);
	cost[1][i][j] = min(cost[1][i][j],cost[1][i][k] + cost[1][k][j]);
      }
    }
  }
}

void input(){
  for(int i = 0 ; i < n ; i++ ){
    int a,b,c,d;
    cin >> a >> b >> c >> d;
    cost[0][a][b] = cost[0][b][a] = c;
    cost[1][a][b] = cost[1][b][a] = d;  
  }
}

void init(){
  for(int i = 0  ; i < m ; i++ ){
    for(int j = 0  ; j < m ; j++ ){
      if(i == j){
	cost[0][i][j] = 0;
	cost[1][i][j] = 0;
      }else{
	cost[0][i][j] = INF; 
	cost[1][i][j] = INF; 
      }
    }
  }
}

int main(){

  while(cin >> n >> m , n+m ){
    m++;
    init();
    input();
    warshall_floyd();
    int k;
    cin >> k;
    for(int i = 0 ; i < k ; i++ ){
      int from,to,r;
      cin >> from >> to >> r; 
      cout << cost[r][from][to] << endl;
    }
  }
  return 0;
}

C++: #include <iostream>
#include <vector>
#include <queue>
#include <algorithm>
using namespace std;

class Node{
public:
	vector< int > e_to;
	vector< int > e_cost;
	
	bool def;
	int min_cost;
	
	Node(){
		def = false;
		min_cost = -1;
	}
};
bool operator>(const Node& ot1, const Node& ot2){
	return ot1.min_cost > ot2.min_cost;
}


class Dijkstra{
	priority_queue< Node, vector< Node >, greater< Node > > que;
	vector< Node > nodes;
	
public:
	void Init(int node_num){
		nodes.resize(node_num);
		for(int i = 0; i < node_num; ++i){
			nodes[i] = Node();
		}
	}
	
	void Put(int id, int to, int cost){
		nodes[id].e_to.push_back(to);
		nodes[id].e_cost.push_back(cost);
	}
	
	int Run(int s, int t){
		
		for(vector< Node >::iterator it = nodes.begin(); it != nodes.end(); ++it){
			it->min_cost = -1;
			it->def = false;
		}
		
		nodes[s].min_cost = 0;
		que.push(nodes[s]);
		
		while(!que.empty()){
			Node def_node = que.top();
			que.pop();
		
			if(def_node.def)continue;
		
			def_node.def = true;
		
			for(int i = 0; i < def_node.e_to.size(); ++i){
				int to = def_node.e_to[i];
				int cost = def_node.min_cost + def_node.e_cost[i];
				
				if(nodes[to].min_cost == -1 || cost < nodes[to].min_cost){
					nodes[to].min_cost = cost;
					que.push(nodes[to]);
				}
			}
		}
		return nodes[t].min_cost;
	}
};

int main(){
	
	int n, m, a, b, c, t, k, p, q, r;
	Dijkstra dijk_cost, dijk_time;
	
	
	while(cin >> n >> m, n){
		dijk_cost.Init(m);
		dijk_time.Init(m);
		
		for(int i = 0; i < n; ++i){
			cin >> a >> b >> c >> t;
			
			dijk_cost.Put(a - 1, b - 1, c);
			dijk_cost.Put(b - 1, a - 1, c);
			
			dijk_time.Put(a - 1, b - 1, t);
			dijk_time.Put(b - 1, a - 1, t);
		}
		
		cin >> k;
		
		for(int i = 0; i < k; ++i){
			cin >> p >> q >> r;
			
			if(r == 0){
				cout << dijk_cost.Run(p - 1, q - 1) << endl;
			}else if(r == 1){
				cout << dijk_time.Run(p - 1, q - 1) << endl;
			}
		}
	}
	
	return 0;
}

C++: #include <cstdio>
#include <cstring>
#include <cstdlib>
#include <cmath>
#include <complex>
#include <string>
#include <sstream>
#include <algorithm>
#include <vector>
#include <queue>
#include <stack>
#include <functional>
#include <iostream>
#include <map>
#include <set>
using namespace std;
typedef pair<int,int> P;
#define pu push
#define pb push_back
#define mp make_pair
#define eps 1e-7
#define INF 200000000
#define EQ(a,b) (abs((a)-(b))<EPS)
int n,m;
int mintime[100][100],mincost[100][100];
void warshall_floyd()
{
	for(int k=0;k<m;k++)
	{
		for(int i=0;i<m;i++)
		{
			for(int j=0;j<m;j++)
			{
				mincost[i][j]=min(mincost[i][j],mincost[i][k]+mincost[k][j]);
				mintime[i][j]=min(mintime[i][j],mintime[i][k]+mintime[k][j]);
			}
		}
	}
	return;
}
int main()
{
	while(1)
	{
		cin >> n >> m;
		if(n==0&&m==0)break;
		for(int i=0;i<m;i++)
		{
			for(int j=0;j<m;j++)
			{
				if(i==j)
				{
					mintime[i][j]=0;
					mincost[i][j]=0;
				}
				else
				{
					mintime[i][j]=INF;
					mincost[i][j]=INF;
				}
			}
		}
		for(int i=0;i<n;i++)
		{
			int a,b,cost,time;
			cin >> a >> b >> cost >> time;
			mincost[a-1][b-1]=cost;
			mincost[b-1][a-1]=cost;
			mintime[a-1][b-1]=time;
			mintime[b-1][a-1]=time;
		}
		warshall_floyd();
		/*
		for(int i=0;i<m;i++)
		{
			for(int j=0;j<m;j++)
			{
				cout << mincost[i][j] << ' ';
			}
			cout << endl;
		}
		for(int i=0;i<m;i++)
		{
			for(int j=0;j<m;j++)
			{
				cout << mintime[i][j] << ' ';
			}
			cout << endl;
		}
		*/
		int k1;
		cin >> k1;
		for(int i=0;i<k1;i++)
		{
			int p,q,r;
			cin >> p >> q >> r;
			if(r==0)
			{
				cout << mincost[p-1][q-1] << endl;
			}
			else
			{
				cout << mintime[p-1][q-1] << endl;
			}
		}
	}
	return 0;
}