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<functional>
#include<algorithm>
#include<iostream>
#include<utility>
#include<string>
#include<vector>
#include<cmath>
#include<stack>
#include<queue>
#include<deque>
#include<map>
#define rep(i,n) for(int i=0;i<n;i++)
#define loop(i,x,n) for(int i=x;i<n;i++)
#define pf push_front
#define pb push_back
#define int long long
using namespace std;
const int INF=1000000007;
int dx[4]={1,0,-1,0};
int dy[4]={0,1,0,-1};
const int N=101;

int cost[N][N];
int tim[N][N];

int bfs(int n,int p,int q,int graph[N][N]){
  vector<int> v(n);
  queue<int> que;
  rep(i,n)v[i]=INF;
  v[p]=0;
  que.push(p);
  int u;
  while(!que.empty()){
    u=que.front(),que.pop();
   
    rep(i,n){
      if(v[i]>v[u]+graph[u][i]){
        v[i]=v[u]+graph[u][i];
        que.push(i);
      }
    }
  }
  return v[q];
}


signed main(){
  int n,m;
  while(cin>>n>>m,n!=0){ 
    rep(i,m)rep(j,m){
      cost[i][j]=(i==j?0:INF);
      tim[i][j]=(i==j?0:INF);
    }
    rep(i,n){
      int a,b,c,t;
      cin>>a>>b>>c>>t;
      a--;b--;
      cost[a][b]=cost[b][a]=c;
      tim[a][b]=tim[b][a]=t;
    }
    int k;
    cin>>k;
    rep(i,k){
      int p,q,r;
      cin>>p>>q>>r;
      p--;q--;
      int ans;
      if(r==0){
        ans=bfs(m,p,q,cost);
      }else{
        ans=bfs(m,p,q,tim);
      }
      cout<<ans<<endl;
    }
  }
  return 0;
}

C++: #include <bits/stdc++.h>
#define INF 114514810
#define FOR(i, r, n) for(int i=(r); i<(n); i++) 
#define REP(i, n) FOR(i, (0), n)

using namespace std;

int n, a, b, c, d, t = 0, sum = INF, ans, nodes = 0, p, q, r, w;
int x[102][102], y[102][102];

int main(){
	while (true){
		cin >> n >> nodes;
		if (n == 0 && nodes == 0) break;
		REP(i, 10)
			REP(j, 10){
			x[i][j] = (i == j ? 0 : INF);
			y[i][j] = (i == j ? 0 : INF);
		}
		REP(i, n){
			cin >> a >> b >> c >> d;
			x[a][b] = x[b][a] = c;
			y[a][b] = y[a][b] = d;
		}
		REP(k, 10)
			REP(i, 10)
			REP(j, 10){
			x[i][j] = min(x[i][j], x[i][k] + x[k][j]);
			y[i][j] = min(y[i][j], y[i][k] + y[k][j]);
		}
		cin >> w;
		REP(k, w){
			cin >> p >> q >> r;
			/*REP(i, nodes + 1){
				REP(j, nodes + 1) t += x[i][j];
				if (sum > t){
					sum = t;
					ans = i;
				}
				t = 0;
			}
			cout << ans << " " << sum << endl;*/
			if (r) cout << y[p][q] << endl;
			else cout << x[p][q] << endl;
		}
		nodes = ans = 0;
		sum = INF;
	}
}

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

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

void read_input() {
  cin >> n >> m;
  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];
  }
  int junk;
  cin >> junk >> junk;
}

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). */  
  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;
}

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