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>
#include <vector>
#include <queue>
#include <tuple>
using namespace std;

template<class T> inline void YES(T condition){ if(condition) cout << "YES" << endl; else cout << "NO" << endl; }
template<class T> inline void Yes(T condition){ if(condition) cout << "Yes" << endl; else cout << "No" << endl; }
template<class T> inline void POSS(T condition){ if(condition) cout << "POSSIBLE" << endl; else cout << "IMPOSSIBLE" << endl; }
template<class T> inline void Poss(T condition){ if(condition) cout << "Possible" << endl; else cout << "Impossible" << endl; }
template<class T> inline void First(T condition){ if(condition) cout << "First" << endl; else cout << "Second" << endl; }
int character_count(string text, char character){ int ans = 0; for(int i = 0; i < text.size(); i++){ ans += (text[i] == character); } return ans; }
long power(long base, long exponent, long module){ if(exponent % 2){ return power(base, exponent - 1, module) * base % module; }else if(exponent){ long root_ans = power(base, exponent / 2, module); return root_ans * root_ans % module; }else{ return 1; }}
struct position{ int y, x; }; position move_pattern[4] = {{-1, 0}, {0, 1}, {1, 0}, {0, -1}}; // double euclidean(position first, position second){ return sqrt((second.x - first.x) * (second.x - first.x) + (second.y - first.y) * (second.y - first.y)); }
template<class itr, class func> void array_output(itr start, itr goal, func out = [](itr x) { return x; } ){ string ans; for(auto i = start; i != goal; i++){ ans += to_string(*i) + " "; } ans.pop_back(); cout << ans << endl; }
template<class itr, class func> void nint_output(itr start, itr goal, func out = [](itr x) { return x; } ){ string ans; for(auto i = start; i != goal; i++){ ans += string(out(*i)) + " "; } ans.pop_back(); cout << ans << endl; }
long gcd(long a, long b){ if(a && b){ return gcd(min(a, b), max(a, b) % min(a, b)); }else{ return a; }}
#define mod long(1e9 + 7)
#define all(x) (x).begin(), (x).end()
#define bitcount(n) __builtin_popcount(n)

template< typename T >
struct edge {
    int src, to;
    T cost;
    
    edge(int to, T cost) : src(-1), to(to), cost(cost) {}
    
    edge(int src, int to, T cost) : src(src), to(to), cost(cost) {}
    
    edge &operator=(const int &x) {
        to = x;
        return *this;
    }
    
    operator int() const { return to; }
};

template< typename T >
using Edges = vector< edge< T > >;
template< typename T >
using WeightedGraph = vector< Edges< T > >;
using UnWeightedGraph = vector< vector< int > >;
template< typename T >
using Matrix = vector< vector< T > >;

template< typename T >
vector< T > dijkstra(WeightedGraph< T > &g, int s)
{
    const auto INF = numeric_limits< T >::max();
    vector< T > dist(g.size(), INF);
    
    using Pi = pair< T, int >;
    priority_queue< Pi, vector< Pi >, greater< Pi > > que;
    dist[s] = 0;
    que.emplace(dist[s], s);
    while(!que.empty()) {
        T cost;
        int idx;
        tie(cost, idx) = que.top();
        que.pop();
        if(dist[idx] < cost) continue;
        for(auto &e : g[idx]) {
            auto next_cost = cost + e.cost;
            if(dist[e.to] <= next_cost) continue;
            dist[e.to] = next_cost;
            que.emplace(dist[e.to], e.to);
        }
    }
    return dist;
}

int main(){
    int n, m;
    cin >> n >> m;
    WeightedGraph<int> roads_cost(m);
    WeightedGraph<int> roads_time(m);
    for(int i = 0; i < n; i++){
        int a, b, cost, time;
        cin >> a >> b >> cost >> time;
        roads_cost[a - 1].push_back(edge<int>(b - 1, cost));
        roads_cost[b - 1].push_back(edge<int>(a - 1, cost));
        roads_time[a - 1].push_back(edge<int>(b - 1, time));
        roads_time[b - 1].push_back(edge<int>(a - 1, time));
    }
    int k;
    cin >> k;
    for(int i = 0; i < k; i++){
        int p, q, r;
        cin >> p >> q >> r;
        if(r){
            cout << dijkstra(roads_time, p - 1)[q - 1] << endl;
        }else{
            cout << dijkstra(roads_cost, p - 1)[q - 1] << endl;
        }
    }
}

C++: #include<iostream>
#include<cstdio>
#include<algorithm>
using namespace std;
#define INF (1<<24)
main(){
  int n,m,k;
  int cost[302][302];
  int time[302][302];
  while(1){
    scanf("%d %d",&n,&m);
    for(int i=1;i<=m;i++)
      for(int j=1;j<=m;j++){cost[i][j]=INF;time[i][j]=INF;}
    if(n==0 && m==0) break;
    for(int i=0;i<n;i++){
      int a,b,c,t;
      scanf("%d %d %d %d",&a,&b,&c,&t);
      cost[a][b]=c;
      cost[b][a]=c;
      time[a][b]=t;
      time[b][a]=t;
    }
    for(int i=1;i<=m;i++)
      for(int j=1;j<=m;j++)
	for(int l=1;l<=m;l++){
	  cost[j][l]=min(cost[j][l],cost[j][i]+cost[i][l]);
	  time[j][l]=min(time[j][l],time[j][i]+time[i][l]);
	}
      
    scanf("%d",&k);
    for(int i=0;i<k;i++){
      int p,q,r;
      scanf("%d %d %d",&p,&q,&r);
      if(r==0) printf("%d\n",cost[p][q]);
      else printf("%d\n",time[p][q]);
    }

  }
}