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>
using namespace std;
#define INF 1<<30
struct edge{int to,cost,time;};
vector<edge> G[101];
int d[101];
bool visited[101];
void dic(int p,int m){
  for(int i=0;i<101;++i) d[i]=INF,visited[i]=false;
  d[p]=0;
  int id;
  for(int i=0;i<m;++i){
    id=-1;
    for(int j=0;j<m;++j){
      if(!visited[j])
        if(id==-1||d[id]>d[j])
          id=j;
    }
    visited[id]=true;
    for(int i=0;i<G[id].size();++i){
      edge e = G[id][i];
      d[e.to]=min(d[e.to],d[id]+e.cost);
    }
  }
}
void dit(int p,int m){
  for(int i=0;i<101;++i) d[i]=INF,visited[i]=false;
  d[p]=0;
  int id;
  for(int i=0;i<m;++i){
    id=-1;
    for(int j=0;j<m;++j){
      if(!visited[j])
        if(id==-1||d[id]>d[j])
          id=j;
    }
    visited[id]=true;
    for(int i=0;i<G[id].size();++i){
      edge e = G[id][i];
      d[e.to]=min(d[e.to],d[id]+e.time);
    }
  }
}
int main(){
  int n,m;
  while(cin>>n>>m,n){
    for(int i=0;i<101;++i) G[i].clear();
    for(int i=0;i<n;++i){
      int a,b,c,t; cin>>a>>b>>c>>t;
      G[a].push_back((edge){b,c,t});
      G[b].push_back((edge){a,c,t});
    }
    int k; cin>>k;
    for(int i=0;i<k;++i){
      int p,q,r; cin>>p>>q>>r;
      if(r) dit(p,m);
      else dic(p,m);
      cout<<d[q]<<endl;
    }
  }
  return 0;
}

C++: #include<queue>
#include<cstdio>
#include<algorithm>

#define rep(i,n) for(int i=0;i<(n);i++)

using namespace std;

// #include"binary_heap.cpp"
// #include"d_heap.cpp"
// #include"pqueue.cpp"

template<class T>
class d_heap_for_Dijkstra{
	static const int N_MAX=3000;
	int n,d,key[N_MAX],pos[N_MAX];
	T val[N_MAX];

	void sift_up(int i,const T &x){
		val[i]=x;
		while(i!=0 && val[(i-1)/d]>val[i]){
			int p=(i-1)/d;
			swap(pos[key[p]],pos[key[i]]);
			swap(key[p],key[i]);
			swap(val[p],val[i]);
			i=p;
		}
	}
	void sift_down(int i,const T &x){
		val[i]=x;
		for(int j,k,c;;i=j){
			j=i;
			for(c=0,k=d*i+1;c<d;c++,k++) if(k<n && val[j]>val[k]) j=k;
			if(j==i) break;
			swap(pos[key[j]],pos[key[i]]);
			swap(key[j],key[i]);
			swap(val[j],val[i]);
		}
	}
public:
	d_heap_for_Dijkstra(int d):n(0),d(d){}
	int find_min()const{ return key[0]; }
	void insert(int u,const T &x){
		int i=n++;
		key[i]=u;
		pos[u]=i;
		sift_up(i,x);
	}
	void delete_min(){
		n--;
		key[0]=key[n];
		sift_down(0,val[n]);
	}
	void decrease_key(int u,const T &x){
		sift_up(pos[u],x);
	}
	bool empty()const{ return n==0; }
	int size()const{ return n; }
	// bool member(int u)const{ return pos[u]}
	void print(){
		puts("-------");
		printf("n=%d:\n",n);
		rep(i,n) printf("  key[%d] = %d, val[%d] = %d\n",i,key[i],i,val[i]);
		rep(i,5) printf("  pos[%d] = %d\n",i,pos[i]);
		puts("-------");
	}
};

const int INF=1<<29;

struct edge{ int v,cost1,cost2; };

int main(){
	for(int m,n;scanf("%d%d",&m,&n),n;){
		vector<edge> G[100];
		rep(i,m){
			int u,v,cost1,cost2; scanf("%d%d%d%d",&u,&v,&cost1,&cost2); u--; v--;
			G[u].push_back((edge){v,cost1,cost2});
			G[v].push_back((edge){u,cost1,cost2});
		}

		int q; scanf("%d",&q);
		while(q--){
			int s,t,type; scanf("%d%d%d",&s,&t,&type); s--; t--;
// printf("s=%d, t=%d\n",s+1,t+1);

			int d[100];
			rep(u,n) d[u]=(u==s?0:INF);
			d_heap_for_Dijkstra<int> H(4);
			H.insert(s,0);
			while(!H.empty()){
// H.print();
				int u=H.find_min();
// printf("  u=%d, d[%d]=%d\n",u,u,d[u]);
				H.delete_min();

				rep(i,G[u].size()){
					const edge &e=G[u][i];
					int d2=d[u]+(type==0?e.cost1:e.cost2);
					if(d[e.v]>d2){
// printf("    v=%d, d2=%d\n",e.v,d2);
						if(d[e.v]==INF) H.insert(e.v,d2);
						else            H.decrease_key(e.v,d2);
						d[e.v]=d2;
					}
				}
			}

			printf("%d\n",d[t]);
		}
	}

	return 0;
}

C++: #include <iostream>
#include <algorithm>
#include <utility>
#include <vector>

const int INF = 10000000;

using Mat = std::vector< std::vector<int> >;

void wf(Mat& adj_mat) {
  int n = adj_mat.size();

  for(int i = 0; i < n; ++i) {     // via node
    for(int j = 0; j < n; ++j) {   // start
      for(int k = 0; k < n; ++k) { // terminal
        adj_mat[j][k] = std::min(adj_mat[j][k], adj_mat[j][i] + adj_mat[i][k]);
      }
    }
  }
}

void answer(int p, int q, int r) {
}

int main() {
  int n, m;
  int a, b, cost, time;

  std::cin >> n >> m;
  std::vector<std::vector<int> > cost_table, time_table;
  cost_table.resize(m);
  time_table.resize(m);
  for(int i = 0; i < m; ++i) {
    cost_table.at(i).resize(m);
    time_table.at(i).resize(m);
    for(int j = 0; j < m; ++j){
      cost_table[i][j] = INF;
      time_table[i][j] = INF;
    }
  }

  for(int i = 0; i < n; ++i){
    std::cin >> a >> b >> cost >> time;
    --a, --b;
    cost_table[a][b] = cost_table[b][a] = cost;
    time_table[a][b] = time_table[b][a] = time;
  }

  wf(cost_table);
  wf(time_table);

  // Query
  int k;
  int p, q, r;
  std::cin >> k;
  for(int i = 0; i < k; ++i){
    std::cin >> p >> q >> r;
    --p, --q;
    if (r == 0)
      std::cout << cost_table[p][q] << std::endl;
    else
      std::cout << time_table[p][q] << std::endl;

  }
}