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++: #define NODE 0
#define WEIGHT 1
#define COST_IDX 0
#define TIME_IDX 1
#define P_IDX 0
#define Q_IDX 1
#define R_IDX 2
#include <iostream>
#include <queue>
#include <vector>
using namespace std;

int n, m, k;
int weights[101][101][2];
int requests[200][3];

bool read_input() {
  cin >> n >> m;
  if (n*m == 0) 
    return false;
  memset(weights, 0, sizeof(int)*101*101*2);
  for (int i = 0; i < n; i++) {
    int a, b, c, t;
    cin >> a >> b >> c >> t;
    weights[a][b][COST_IDX] = weights[b][a][COST_IDX] = c;
    weights[a][b][TIME_IDX] = weights[b][a][TIME_IDX] = t;
  }
  cin >> k;
  for (int i = 0; i < k; i++) {
    cin >> requests[i][P_IDX] >> requests[i][Q_IDX] >> requests[i][R_IDX];
  }
  return true;
}

int resolve_request(int i_th) {
  int p, q, r;
  p = requests[i_th][P_IDX];
  q = requests[i_th][Q_IDX];
  r = requests[i_th][R_IDX];
  
  int weight_sum_map[101];
  int in_queue[101] = {}; // set all to 0
  memset(weight_sum_map, -1, sizeof(int)*101);
  
  /* starting node has weight_sum of 0 */
  weight_sum_map[p] = 0;
  in_queue[p] = 1;
  int current_node = p; // first in queue is p

  while (current_node != q) {
    int weight_sum = weight_sum_map[current_node];
    in_queue[current_node] = 0;
    
    for (int i = 1; i < 101; i++) {
      if (!weights[current_node][i][r]) 
	continue;
      int adj_node = i;
      int w = weights[current_node][adj_node][r];
      int new_weight_sum =  weight_sum + w;
      if (weight_sum_map[adj_node] == -1 || new_weight_sum < weight_sum_map[adj_node]) {
	weight_sum_map[adj_node] = new_weight_sum;
	in_queue[adj_node] = 1;
      }
    }
    
    int min_sum = -1;
    for (int i = 1; i < 101; i++) {
      if (in_queue[i] && (min_sum == -1 || weight_sum_map[i] < min_sum)) {
	min_sum = weight_sum_map[i];
	current_node = i;
      }
    }
  }
  return weight_sum_map[q];
}

void solve() {
  for (int i = 0; i < k; i++)
    cout << resolve_request(i) << endl;
}

int main() {
  while(read_input()) {
    solve();
  }
  return 0;
}

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

#define iota(i,n,b,s) for(int i=int(b);i!=int((b)+(s)*(n));i+=(s))
#define range(i,n,m) iota(i,(((n)>(m))?((n)-(m)+1):((m)-(n)+1)),(n),((n)>(m)?-1:1))
#define rep(i,n) iota(i,(n),0,1)

#define INF (1e9)
#define EPS (1e-9)
#define cons(a,b) (make_pair(a,b))
#define car(a) (a.first)
#define cdr(a) (a.second)
#define cadr(a) (car(cdr(a)))
#define cddr(a) (cdr(cdr(a)))
#define all(a) a.begin(), a.end()
#define trace(var) cerr<<">>> "<<#var<<" = "<<var<<endl;

typedef long long INTEGER;
typedef double FLOAT;

template<class S, class T>
ostream& operator<<(ostream& os, pair<S,T> p) {
  os << '(' << car(p) << ", " << cdr(p) << ')';
  return os;
}

template<class T>
ostream& operator<<(ostream& os, vector<T> v) {
  os << v[0];
  for (int i=1, len=v.size(); i<len; ++i) os << ' ' << v[i];
  return os;
}

const int MM = 100;
int cost[MM][MM];
int toki[MM][MM];

int main() {

entry:;
  int n, m; cin >> m >> n;
  if (n + m == 0) return 0;

  rep (i, n) {
    rep (j, n) {
      cost[i][j] = INF;
      toki[i][j] = INF;
    }
    cost[i][i] = 0;
    toki[i][i] = 0;
  }

  rep (i, m) {
    int a, b, c, t;
    cin >> a >> b >> c >> t;
    --a; --b;
    cost[a][b] = cost[b][a] = c;
    toki[a][b] = toki[b][a] = t;
  }

  rep (k, n) {
    rep (i, n) {
      rep (j, n) {
        cost[i][j] = min(cost[i][j], cost[i][k] + cost[k][j]);
        toki[i][j] = min(toki[i][j], toki[i][k] + toki[k][j]);
      }
    }
  }

  //rep (i,n) { rep(j,n) { cout << cost[i][j] << ' '; } cout << endl; }

  int k; cin >> k;
  rep (i, k) {
    int a, b, t;
    cin >> a >> b >> t;
    --a; --b;
    if (t) {
      cout << toki[a][b] << endl;
    } else {
      cout << cost[a][b] << endl;
    }
  }

  goto entry;

  return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
#define INF 1000000

int main() {
    while (true) {
        int n, m;
        cin >> n >> m;
        
        if (n==0 && m==0) {
            break;
        }
        
        int d_cost[m][m];
        int d_time[m][m];
        
        for (int i=0; i<m; i++) {
            for (int j=0; j<m; j++) {
                d_cost[i][j] = INF;
                d_time[i][j] = INF;
            }
        }
        
        for (int i=0; i<n; i++) {
            int ai, bi, cost_i, time_i;
            cin >> ai >> bi >> cost_i >> time_i;
            d_cost[ai-1][bi-1] = cost_i;
            d_cost[bi-1][ai-1] = cost_i;
            d_time[ai-1][bi-1] = time_i;
            d_time[bi-1][ai-1] = time_i;
        }
        
        for (int k=0; k<m; k++) {
            for (int i=0; i<m; i++) {
                for (int j=0; j<m; j++) {
                    d_cost[i][j] = min(d_cost[i][j], d_cost[i][k]+d_cost[k][j]);
                    d_time[i][j] = min(d_time[i][j], d_time[i][k]+d_time[k][j]);
                }
            }
        }
        
        int k;
        cin >> k;
        
        for (int i=0; i<k; i++) {
            int pi, qi, ri;
            cin >> pi >> qi >> ri;
            
            if (ri==0) {
                cout << d_cost[pi-1][qi-1] << endl;
            }
            else {
                cout << d_time[pi-1][qi-1] << endl;
            }
        }
    }
}