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++: #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 <unordered_map>
#include <queue>
#include <vector>
using namespace std;

int n, m, k;
unordered_map<int, unordered_map<int, int*> > weights;
int **requests;

bool read_input() {
  cin >> n >> m;
  if (n*m == 0) 
    return false;
  for (int i = 0; i < n; i++) {
    int a, b, c, t;
    cin >> a >> b >> c >> t;
    weights[a][b] = new int[2];
    weights[b][a] = new int[2];
    weights[a][b][COST_IDX] = weights[b][a][COST_IDX] = c;
    weights[a][b][TIME_IDX] = weights[b][a][TIME_IDX] = t;
  }
  cin >> k;
  requests = new int*[k];
  for (int i = 0; i < k; i++) {
    requests[i] = new int[3];
    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];

  /* keep track of latest weight_sum of each node since values 
   * in priority queue might not be up to date (since STL prioroty 
   * queue does not support value change, ignore popped itmes
   * that does not match values in this map). */  
  unordered_map<int, int> weight_sum_map;
  
  /* starting node has weight_sum of 0 */
  weight_sum_map[p] = 0;

  /* create priority queue and push p into it as the initial element */
  auto cmp = [](int *a, int *b) { return a[WEIGHT] > b[WEIGHT]; };
  priority_queue<int*, vector<int*>, decltype(cmp)> pq(cmp); 
  int *itm = new int[2];
  itm[NODE] = p;
  itm[WEIGHT] = 0;
  pq.push(itm);

  while (!pq.empty()) {
    itm = pq.top(); 
    int weight_sum = itm[WEIGHT];
    int node = itm[NODE];

    /* release allocated mem and remove from priority queue*/
    delete[] itm;
    pq.pop();

    // if q was popped, release all allocated mem and break 
    if (node == q) {/*
      while (!pq.empty()) {
	itm = pq.top();
	delete[] itm;
	pq.pop();
	}*/
      break;
    }

    /* ignore if wight_sum value not up to date */
    if (weight_sum != weight_sum_map[node]) {
      continue;
    }
    auto connections = weights[node];
    for (auto itr = connections.begin(); itr != connections.end(); itr++) {
      int adj_node = itr->first;
      int w = itr->second[r]; // get the requested weight type r == 0(cost) or 1(time)
      int new_weight_sum = weight_sum + w;
      if (weight_sum_map.count(adj_node) == 0 || new_weight_sum < weight_sum_map[adj_node]) {
	weight_sum_map[adj_node] = new_weight_sum;
	itm = new int[2];
	itm[NODE] = adj_node;
	itm[WEIGHT] = new_weight_sum;
	pq.push(itm);
      }
    }
  }
  return weight_sum_map[q];
}

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

void cleanup() {/*
  for (int i = 0; i < k; i++) {
    delete[] requests[i];
  }
  delete[] requests;
		*/
  /*
  for (auto itr_a = weights.begin(); itr_a != weights.end(); itr_a++) {
    auto m = itr_a->second;
    for (auto itr_b = m.begin(); itr_b != m.end(); itr_b++) {
      delete[] itr_b->second;
    }
    m.clear();
    }*/
  weights.clear();
}

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

C++: #include<bits/stdc++.h>
#define ll long long int
#define FOR(i,a,b) for(ll i=(ll)(a);i<(ll)(b);i++)
#define REP(i,n) FOR(i,0,n)
#define REP1(i,n) FOR(i,1,n)
#define MIN(a, b) ((a)<(b)?(a):(b))
#define INF 10e6
using namespace std;
 /*temp*/

int main(){
    int n, m, l;
    while(cin>>m>>n,n){
        int cost[n][n],tim[n][n];
        // set table
        REP(i,n){
            REP(j,n){
                cost[i][j]=tim[i][j]=INF;
            }
            cost[i][i]=tim[i][i]=0;
        }
        // read
        REP(i,n){
            int a,b,c,t;
            a--;
            b--;
            cost[a][b]=cost[b][a]=MIN(c,cost[a][b]);
            tim[a][b]=tim[b][a]=MIN(t,tim[a][b]);
        }
        // Warshall???Floyd Algorithm
        REP(a,n){
            REP(b,a+1){
                REP(k,n){
                    cost[a][b]=cost[b][a]=MIN(cost[a][b],cost[a][k]+cost[k][b]);
                    tim[a][b]=tim[b][a]=MIN(tim[a][b],tim[a][k]+tim[k][b]);
                }
            }
        }
        // 
        int q;
        cin>>q;
        REP(i,q){
            int s,d,type;
            cin>>s>>d>>type;
            s--;
            d--;
            cout<<type==0?cost[s][d]:tim[s][d]<<'\n';
        }
    }
    return 0;
}

C++: #include <iostream>
#include <algorithm>
using namespace std;
int main(){
  int road1[111][111];
  int road2[111][111];
  int n,m;
  int a,b,cost,time;
  int p,q,r;
  int x;
  while(1){
    for(int i=0;i<101;i++){
      for(int j=0;j<101;j++){
	road1[i][j]=road2[i][j]=1111111;
      }
    }
    cin >> n >> m;
    if(n==0 && m==0)break;
    for(int i=0;i<n;i++){
      cin >> a >> b >> cost >> time;
      road1[a][b]=road1[b][a]=cost;
      road2[a][b]=road2[b][a]=time;
    }

    for(int k=1;k<=n;k++){
      for(int i=1;i<=n;i++){
	for(int j=1;j<=n;j++){
	  if(road1[i][j]>road1[i][k]+road1[k][j]){
	    road1[i][j]=road1[i][k]+road1[k][j];
	  }
	  if(road2[i][j]>road2[i][k]+road2[k][j]){
	    road2[i][j]=road2[i][k]+road2[k][j];
	  }
	}
      }
    }
    
    cin >> x;
    for(int i=1;i<=x;i++){
      cin >> p >> q >> r;
      cout << (r==0 ? road1[p][q] : road2[p][q]) << endl;
    }
  }
}