Lennot

#!/usr/bin/env python
# -*- coding: utf-8 -*-

import sys
from sys import stdin
from sys import stdout

maxint = sys.maxint

def readline():
    return stdin.readline().strip()

line1 = readline().split(' ')
# Kaupunkeja
n = int(line1[0])
# Lentoja
m = int(line1[1])

class Flight:
    def __init__(self, a, b, h):
        self.fr = a
        self.to = b
        self.price = int(h)

class City:
    def __init__(self, aid):
        self.total_price_even = maxint
        self.even_price_set = False
        self.total_price_odd = maxint
        self.odd_price_set = False
        self.calculated = False
        self.con_fr = []
        self.con_to = []
        self.aid = aid
        self.remove = False
    def __eq__(self, other):
        return (isinstance(other, self.__class__)
            and self.aid == other.aid)


flights = []
cities = []
for c in xrange(n):
    cities.append(City(c))

uncalculated = list(cities)

for f in xrange(m):
    row = readline().split(' ')
    flight = Flight(cities[int(row[0])-1], cities[int(row[1])-1], row[2])
    flights.append(flight)
    flight.fr.con_to.append(flight)
    flight.to.con_fr.append(flight)

# Purge all unnecessary cities
removes = []
for city_i in xrange(n):
    if city_i > 0:
        if city_i < len(cities)-1:
            city = cities[city_i]
            if len(city.con_to) == 0 or len(city.con_fr) == 0:
                for flight in city.con_to:
                    flights.remove(flight)
                for flight in city.con_fr:
                    flights.remove(flight)
                removes.append(city)
        else:
            break
for city in removes:
    cities.remove(city)

start = cities[0]
end = cities[-1]
current = cities[0]

current.total_price_even = 0
current.even_price_set = True



found = False
while not found:
    for flight in current.con_to:
        city = flight.to
        if not city.calculated:
            if current.even_price_set:
                new_odd_price = current.total_price_even + flight.price
                if new_odd_price < city.total_price_odd:
                    city.total_price_odd = new_odd_price
                    city.odd_price_set = True
            
            if current.odd_price_set:
                new_even_price = current.total_price_odd
                if new_even_price < city.total_price_even:
                    city.total_price_even = new_even_price
                    city.even_price_set = True
    uncalculated.remove(current)
    current.calculated = True
    if current == end:
        found = True
        print(min(current.total_price_even, current.total_price_odd))
        break
    
    smallest_price = maxint
    for city in uncalculated:
        # cityprice = city.total_price_even + city.total_price_odd
        cityprice = 0
        if city.even_price_set:
            cityprice += city.total_price_even
        if city.odd_price_set:
            cityprice += city.total_price_odd
        if cityprice != 0:
            if cityprice < smallest_price:
                smallest = city
                smallest_price = cityprice
    
    current = smallest

Test 1

Group: 1

Verdict: WRONG ANSWER

Test 2

Group: 1

Verdict: ACCEPTED

Test 3

Group: 1

Verdict: ACCEPTED

Test 4

Group: 1

Verdict: ACCEPTED

Test 5

Group: 1

Verdict: ACCEPTED

Test 6

Group: 2

Verdict: WRONG ANSWER

Test 7

Group: 2

Verdict: WRONG ANSWER

Test 8

Group: 2

Verdict: WRONG ANSWER

Test 9

Group: 2

Verdict: WRONG ANSWER

Test 10

Group: 2

Verdict: WRONG ANSWER

Test 11

Group: 3

Verdict: RUNTIME ERROR

Test 12

Group: 3

Verdict: RUNTIME ERROR

Test 13

Group: 3

Verdict: RUNTIME ERROR

Test 14

Group: 3

Verdict: RUNTIME ERROR

Test 15

Group: 3

Verdict: RUNTIME ERROR

Test 16

Group: 3

Verdict: RUNTIME ERROR

Test 17

Group: 3

Verdict: RUNTIME ERROR