Go: // Warshall–Floyd Algorithm

package main

import (
	"bufio"
	"os"
	"strings"
	"strconv"
	"fmt"
)

var scanner = bufio.NewScanner(os.Stdin)

const INF = 0x7FFFFFFF

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
				} else {
					c_dist[i][j] = c_matrix[i][j]
				}
				if c_matrix[i][j] == 0{
					c_prev[i][j] = -1
				} else {
					c_prev[i][j] = i
				}
				if t_matrix[i][j] == 0{
					t_dist[i][j] = INF
				} else {
					t_dist[i][j] = t_matrix[i][j]
				}
				if t_matrix[i][j] == 0{
					t_prev[i][j] = -1
				} else {
					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]
					t_newlen := t_dist[i][k] + t_dist[k][j]
					if c_newlen < c_dist[i][j] {
						c_dist[i][j] = c_newlen
						c_prev[i][j] = c_prev[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])
			}
		}
	}
}

Python: """ Created by Jieyi on 7/28/16. """
import io
import sys
from collections import defaultdict
import heapq

if len(sys.argv) > 1:
    filename = sys.argv[1]
    inp = ''.join(open(filename, "r").readlines())
    sys.stdin = io.StringIO(inp)


def dijkstra(graph, start, end, total_vertices):
    h = []
    shortest_path = [0 if i == start else sys.maxsize for i in range(total_vertices + 1)]
    heapq.heappush(h, (start, 0))

    while True:
        vertex, value = heapq.heappop(h)
        if end == vertex:
            break

        for k, v in graph.get(vertex):
            if shortest_path[k] > value + v:
                shortest_path[k] = value + v
                heapq.heappush(h, (k, shortest_path[k]))

    return shortest_path


def algorithm():
    while True:
        n, s = map(int, input().split())
        if n == 0 and s == 0:
            break

        # Create two maps.
        g_money = defaultdict(list)
        g_time = defaultdict(list)

        # Set two maps.
        for _ in range(n):
            start, end, money, time = map(int, input().split())
            g_money[start].append((end, money))
            g_money[end].append((start, money))
            g_time[start].append((end, time))
            g_time[end].append((start, time))

        # Calculate the shortest path.
        for n in range(int(input())):
            start, end, category = list(map(int, input().split()))
            m = {0: g_money, 1: g_time}.get(category)
            ans = dijkstra(m, start, end, s)
            print(ans[end])


def main():
    algorithm()


if __name__ == '__main__':
    main()

Python: # coding: utf-8
class Route:
    def __init__(self, station_number, price, time):
        self.station_number = station_number
        self.price = price
        self.time = time

class Station:
    def __init__(self):
        self.routes = []
    def addRoute(self,route):
        self.routes.append(route)

class Path:
    def __init__(self, now_station, next_station, price, time):
        self.now_station = now_station
        self.next_station = next_station
        self.price = price
        self.time = time

def search_path(stations, come_from, go_to, search_type):
    result = []
    q = []
    for distination in stations[come_from].routes:
        new_path = Path(come_from, distination.station_number, distination.price, distination.time)
        q.append(new_path)
    while len(q) > 0:
        path = q.pop(0)
        if path.next_station == go_to:
            r = path.price if search_type == 0 else path.time
            result.append(r)
        for distination in stations[path.next_station].routes:
            update_price = path.price + distination.price
            update_time = path.time + distination.time
            next_path = Path(path.next_station, distination.station_number, update_price, update_time)
            q.append(next_path)
    print(sorted(result)[0])

route_count, station_count = map(int, input().split(" "))
stations = [Station() for i in range(station_count)]
for read_line in range(route_count):
    come_from, go_to, price, time = map(int, input().split(" "))
    route = Route(go_to - 1, price, time)
    stations[come_from - 1].addRoute(route)
search_count = int(input())
for read_line in range(search_count):
    come_from, go_to, search_type = map(int, input().split())
    search_path(stations, come_from - 1, go_to - 1, search_type)

Python: def warshall_floyd(d):
    for k in range(len(d)):
        for i in range(len(d)):
            for j in range(len(d)):
                if d[i][j] > d[i][k] + d[k][j]:
                    d[i][j] = d[i][k] + d[k][j]

import sys
f = sys.stdin

while True:
    n, m = map(int, f.readline().split())
    if n == 0:
        break
    abct = [list(map(int, f.readline().split())) for _ in range(n)]
    
    d = [[[float('inf')] * m for i in range(m)], [[float('inf')] * m for i in range(m)]]
    
    for ai, bi, ci, ti in abct:
        d[0][ai - 1][bi - 1] = ci
        d[1][ai - 1][bi - 1] = ti

    warshall_floyd(d[0])
    warshall_floyd(d[1])
        
    for i in range(int(f.readline())):
        p, q, r = map(int, f.readline().split())
        print(d[r][p - 1][q - 1])