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
			t_matrix[a-1][b-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 <bits/stdc++.h>

const int MOD = 1e9 + 7;
const int iINF = 1000000000;
const long long int llINF = 1000000000000000000;
const double PI = acos(-1.0);
#define rep(i, n) for (int i = 0; i < (n); i++)

using namespace std;
using ll = long long int;
using P = pair<int, int>;
using edge = struct
{
    int to;
    int cost;
};

int dx[4] = {1, 0, -1, 0};
int dy[4] = {0, 1, 0, -1};

ll costs[100][100];
ll times[100][100];

void Warshall_Floyd(int N, ll (&cost)[100][100])
{
    rep(k, N) rep(i, N) rep(j, N)
        cost[i][j] = min(cost[i][j], cost[i][k] + cost[k][j]);
}

int main()
{
    int N, M;
    while (cin >> N >> M && N)
    {
        rep(i, 100) rep(j, 100) costs[i][j] = llINF;
        rep(i, 100) rep(j, 100) times[i][j] = llINF;

        rep(i, N)
        {
            ll a, b, c, t;
            cin >> a >> b >> c >> t;
            a--;
            b--;

            costs[a][b] = min(costs[a][b], c);
            costs[b][a] = min(costs[b][a], c);

            times[a][b] = min(times[a][b], t);
            times[b][a] = min(times[b][a], t);
        }

        Warshall_Floyd(N, costs);
        Warshall_Floyd(N, times);

        int K;
        cin >> K;

        int p, q, r;

        rep(i, K)
        {
            cin >> p >> q >> r;
            p--;
            q--;

            cout << (r == 1 ? times[p][q] : costs[p][q]) << endl;
        }
    }
    return 0;
}

C++: #include <iostream>
#include <sstream>
#include <fstream>
#include <vector>
#include <list>
#include <set>
#include <map>
#include <stack>
#include <queue>
#include <algorithm>
#include <numeric>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <climits>
#include <cmath>
using namespace std;

#define REP(i,n) for(int i=0;i<(int)n;++i)
#define FOR(i,c) for(__typeof((c).begin())i=(c).begin();i!=(c).end();++i)
#define ALL(c) (c).begin(), (c).end()
#define INF 1<<24

typedef int Weight;
struct Edge {
  int src, dst;
  Weight weight;
  Edge(int src, int dst, Weight weight) :
    src(src), dst(dst), weight(weight) { }
};
bool operator < (const Edge &e, const Edge &f) {
  return e.weight != f.weight ? e.weight > f.weight : // !!INVERSE!!
    e.src != f.src ? e.src < f.src : e.dst < f.dst;
}
typedef vector<Edge> Edges;
typedef vector<Edges> Graph;

typedef vector<Weight> Array;
typedef vector<Array> Matrix;

void shortestPath(const Graph &g, int s,
    vector<Weight> &dist, vector<int> &prev) {
  int n = g.size();
  dist.assign(n, INF); dist[s] = 0;
  prev.assign(n, -1);
  priority_queue<Edge> Q; // "e < f" <=> "e.weight > f.weight"
  for (Q.push(Edge(-2, s, 0)); !Q.empty(); ) {
    Edge e = Q.top(); Q.pop();
    if (prev[e.dst] != -1) continue;
    prev[e.dst] = e.src;
    FOR(f,g[e.dst]) {
      if (dist[f->dst] > e.weight+f->weight) {
        dist[f->dst] = e.weight+f->weight;
        Q.push(Edge(f->src, f->dst, e.weight+f->weight));
      }
    }
  }
}
vector<int> buildPath(const vector<int> &prev, int t) {
  vector<int> path;
  for (int u = t; u >= 0; u = prev[u])
    path.push_back(u);
  reverse(path.begin(), path.end());
  return path;
}

int main() {
    int n, m;
    while ( cin >> n >> m ) {
        if ( n == 0 && m == 0 ) break;
        Graph C(m);
        Graph T(m);
        for ( int i = 0; i < n; i++ ) {
            int a, b, c, t;
            cin >> a >> b >> c >> t;
            a--;
            b--;
            C[a].push_back( Edge( a, b, c ) );
            C[b].push_back( Edge( b, a, c ) );
            T[a].push_back( Edge( a, b, t ) );
            T[b].push_back( Edge( b, a, t ) );
        }

        int k;
        cin >> k;
        for ( int i = 0; i < k; i++ ) {
            int p, q, r;
            cin >> p >> q >> r;
            p--;
            q--;
            vector <Weight> Q;
            vector <int> I;
            shortestPath( (r==0?C:T), p, Q, I );
            cout << Q[q] << endl;
        }
    }
    return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
typedef long long ll;

#define EPS (1e-7)
#define INF (1e9)
#define PI (acos(-1))
#define MAXN 1000
#define rep(i,n) for (int i = 0; i < (n); ++i)
const ll mod = 1e9+7;

int co[MAXN][MAXN];
int ti[MAXN][MAXN];

int main() {
    int n, m, a, b;
    while (cin >> n >> m, n) {

        rep(i, m) {
            rep(j, m) {
                if(i==j) {
                    co[i][j] = 0;
                    ti[i][j] = 0;
                } else {
                    co[i][j] = INF;
                    ti[i][j] = INF;
                }
            }
        }

        int t, c;
        rep(i, n) {
            cin >> a >> b >> c >> t;
            --a; --b;
            co[a][b] = c;
            co[b][a] = c;
            ti[a][b] = t;
            ti[b][a] = t;
        }

        rep(k, m) {
            rep(i, m) {
                rep(j, m) {
                    ti[i][j] = min(ti[i][j], ti[i][k]+ti[k][j]);
                    co[i][j] = min(co[i][j], co[i][k]+co[k][j]);
                }
            }
        }

        int K, r;
        cin >> K;
        rep(re, K) {
            cin >> a >> b >> r;
            --a; --b;

            if (r) cout << ti[a][b] << endl;
            else cout << co[a][b] << endl;
        }
    }
}