Problem: There are N towns numbered 1 to N and M roads. The i-th road connects Town A_i and Town B_i bidirectionally and has a length of C_i.  Takahashi will travel between these towns by car, passing through these roads. The fuel tank of his car can contain at most L liters of fuel, and one liter of fuel is consumed for each unit distance traveled. When visiting a town while traveling, he can full the tank (or choose not to do so). Travel that results in the tank becoming empty halfway on the road cannot be done.  Process the following Q queries:    * The tank is now full. Find the minimum number of times he needs to full his tank while traveling from Town s_i to Town t_i. If Town t_i is unreachable, print -1.

Submission attempts (in order):
import numpy as np
from scipy.sparse.csgraph import bellman_ford


def solve(N,L,edges,queries):

    graph = np.zeros((N,N),dtype=int)
    for a,b,c in edges:
        graph[a-1,b-1] = c
        graph[b-1,a-1] = c

    dist = bellman_ford(graph, directed=False)
    dist = (dist<=L)
    print('test')
    exit()
    dist = bellman_ford(dist, directed=False)
    res = []
    for a,b in queries:
        d = dist[a-1,b-1]
        res.append(int(d-1) if d != float('inf') else -1)
    return res

import sys
read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline

if __name__ == '__main__':

    t = read().split()

    N,M,L = map(int,t[:3])

    m = map(int,t[3:M*3+3])
    edges = zip(m,m,m)

    Q = int(t[M*3+3])
    m = map(int, t[M*3+4:])
    queries = zip(m,m)

    print(*solve(N,L,edges,queries), sep='\n')

import numpy as np
from scipy.sparse.csgraph import bellman_ford


def solve(N,L,edges,queries):

    graph = np.zeros((N,N),dtype=int)
    for a,b,c in edges:
        graph[a-1,b-1] = c
        graph[b-1,a-1] = c

    print('test')
    exit()
    dist = bellman_ford(graph, directed=False)
    dist = (dist<=L)
    dist = bellman_ford(dist, directed=False)
    res = []
    for a,b in queries:
        d = dist[a-1,b-1]
        res.append(int(d-1) if d != float('inf') else -1)
    return res

import sys
read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline

if __name__ == '__main__':

    t = read().split()

    N,M,L = map(int,t[:3])

    m = map(int,t[3:M*3+3])
    edges = zip(m,m,m)

    Q = int(t[M*3+3])
    m = map(int, t[M*3+4:])
    queries = zip(m,m)

    print(*solve(N,L,edges,queries), sep='\n')

import numpy as np
from scipy.sparse.csgraph import floyd_warshall


def solve(N,L,edges,queries):

    graph = np.zeros((N,N),dtype=int)
    for a,b,c in edges:
        graph[a-1,b-1] = c
        graph[b-1,a-1] = c

    dist = floyd_warshall(graph, directed=False)
    dist = (dist<=L)
    dist = floyd_warshall(dist, directed=False)
    res = []
    for a,b in queries:
        d = dist[a-1,b-1]
        res.append(int(d-1) if d != float('inf') else -1)
    return res

import sys
read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline

if __name__ == '__main__':

    t = read().split()

    N,M,L = map(int,t[:3])

    m = map(int,t[3:M*3+3])
    edges = zip(m,m,m)

    Q = int(t[M*3+3])
    m = map(int, t[M*3+4:])
    queries = zip(m,m)

    print(*solve(N,L,edges,queries), sep='\n')

Verdicts: Wrong Answer

Wrong Answer

Accepted