Problem p03682 (python)

Fixed submission:
# -*- coding: utf-8 -*-
"""
Created on Thu Sep 20 21:40:30 2018
ABC065D
@author: maezawa
i=0...n (0-origin)
"""
import heapq
import sys
input = sys.stdin.readline

n = int(input())
a = [[] for _ in range(n)]
b = [[] for _ in range(n)]
for i in range(n): # i is a name of the city (0-origin)
    xy = list(map(int, input().split()))
    a[i]=[xy[0],i]
    b[i]=[xy[1],i]

a.sort()
b.sort()
#print(a) 
#print(b)

# making adj list
adj = [[] for _ in range(n)]
for [x0, j0], [x1, j1]  in zip(a, a[1:]):
    adj[j0].append([x1-x0, j1])
    adj[j1].append([x1-x0, j0])
for [y0, j0], [y1, j1] in zip(b, b[1:]):
    adj[j0].append([y1-y0, j1])
    adj[j1].append([y1-y0, j0])

#print(adj)
    
# Prim's algorithm
#d = [10**10]*n
visited = [False]*n
h = []
s = 0
heapq.heappush(h, [0, s])
cnt = 0
totalcost = 0 
while h:
    cost, node = heapq.heappop(h)
    #if visited[node] != True and cost < d[node]:
    if visited[node] != True:        
        #d[node] = cost
        visited[node] = True
        totalcost += cost
        cnt += 1
        if cnt == n:
            break
        for edge in adj[node]:
            if visited[edge[1]]:
                continue
            heapq.heappush(h, edge)
            
#print(d)
print(totalcost)

Buggy submission (verdict: Runtime Error):
# -*- coding: utf-8 -*-
"""
Created on Thu Sep 20 21:40:30 2018
ABC065D
@author: maezawa
i=0...n (0-origin)
"""
import heapq

n = int(input())
a = []
b = []
for i in range(n): # i is a name of the city (0-origin)
    xy = list(map(int, input().split()))
    a.append([i,xy[0]])
    b.append([i,xy[1]])

a.sort(key=lambda x: x[1])
b.sort(key=lambda x: x[1])
#print(a) 
#print(b)

# making adj list
adj = [[] for _ in range(n)]
for i, x in a[:-1]:
    adj[i].append([a[i+1][1]-x, a[i+1][0]])
    adj[a[i+1][0]].append([a[i+1][1]-x, i])
for i, y in b[:-1]:
    adj[i].append([b[i+1][1]-y, b[i+1][0]])
    adj[b[i+1][0]].append([b[i+1][1]-y, i])

#print(adj)
    
# Prim's algorithm
d = [10**10]*n
visited = [False]*n
h = []
s = 0
heapq.heappush(h, [0, s])
cnt = 0
while h:
    cost, node = heapq.heappop(h)
    if visited[node] != True and cost < d[node]:
        d[node] = cost
        visited[node] = True
        cnt += 1
        if cnt == n:
            break
        for edge in adj[node]:
            if visited[edge[1]] == True:
                continue
            heapq.heappush(h, edge)
            
#print(d)
print(sum(d))

Buggy submission (verdict: Runtime Error):
# -*- coding: utf-8 -*-
"""
Created on Thu Sep 20 21:40:30 2018
ABC065D
@author: maezawa
i=0...n (0-origin)
"""
import heapq

n = int(input())
a = []
b = []
for i in range(n): # i is a name of the city (0-origin)
    xy = list(map(int, input().split()))
    a.append([i,xy[0]])
    b.append([i,xy[1]])

a.sort(key=lambda x: x[1])
b.sort(key=lambda x: x[2])
#print(a) 
#print(b)

# making adj list
adj = [[] for _ in range(n)]
for i in range(len(a)-1):
    adj[a[i][0]].append([a[i+1][1]-a[i][1], a[i+1][0]])
    adj[a[i+1][0]].append([a[i+1][1]-a[i][1], a[i][0]])
for i in range(len(b)-1):
    adj[b[i][0]].append([b[i+1][1]-b[i][1], b[i+1][0]])
    adj[b[i+1][0]].append([b[i+1][1]-b[i][1], b[i][0]])

#print(adj)
    
# Prim's algorithm
d = [10**10]*n
visited = [False]*n
h = []
s = 0
heapq.heappush(h, [0, s])
cnt = 0
while h:
    current = heapq.heappop(h)
    if visited[current[1]] != True and current[0] < d[current[1]]:
        d[current[1]] = current[0]
        visited[current[1]] = True
        cnt += 1
        if cnt == n:
            break
        for edge in adj[current[1]]:
            if visited[edge[1]] == True:
                continue
            heapq.heappush(h, edge)
            
#print(d)
print(sum(d))