Problem p03995 (python)

Fixed submission:
from collections import defaultdict
import sys
sys.setrecursionlimit(10**6)

def ReadInput():
	return [int(i) for i in input().split(" ")]

(R, C) = ReadInput()
N = int(input())
VectorSet = set() 
Grid = defaultdict(list)
for i in range(N):
	(r, c, a) = ReadInput()
	Grid[("R", r)].append((("C", c), a))
	Grid[("C", c)].append((("R", r), a))
	VectorSet.add(("R", r))
	VectorSet.add(("C", c))

def iteration(vector):
	VectorSet.discard(vector)
	for (v, a) in Grid[vector]:
		temp = a - VectorCover[vector]
		if (v in VectorCover):
			if(temp != VectorCover[v]):
				print("No")
				exit()
		else:
			VectorCover[v] = temp
			iteration(v) 

while(len(VectorSet) != 0):
	vector = VectorSet.pop()
	VectorCover = dict() 
	VectorCover[vector] = 0
	iteration(vector)
	minR = min(a for (p, a) in VectorCover.items() if (p[0] == "R"))
	minC = min(a for (p, a) in VectorCover.items() if (p[0] == "C"))
	if (minR + minC < 0):
		print("No")
		exit()

print("Yes")

Buggy submission (verdict: Runtime Error):
from collections import defaultdict
def ReadInput():
	return [int(i) for i in input().split(" ")]
(R, C) = ReadInput()
N = int(input())
VectorSet = set() 
Grid = defaultdict(list)
for i in range(N):
	(r, c, a) = ReadInput()
	Grid[("R", r)].append((("C", c), a))
	Grid[("C", c)].append((("R", r), a))
	VectorSet.add(("R", r))
	VectorSet.add(("C", c))
def iteration(vector):
	VectorSet.discard(vector)
	for (v, a) in Grid[vector]:
		temp = a - VectorCover[vector]
		if (v in VectorCover):
			if(temp != VectorCover[v]):
				print("No")
				exit()
		else:
			VectorCover[v] = temp
			iteration(v) 
while(len(VectorSet) != 0):
	vector = VectorSet.pop()
	VectorCover = dict() 
	VectorCover[vector] = 0
	iteration(vector)
	minR = min(a for (p, a) in VectorCover.items() if (p[0] == "R"))
	minC = min(a for (p, a) in VectorCover.items() if (p[0] == "C"))
	if (minR + minC < 0):
		print("No")
		exit()
print("Yes")

Buggy submission (verdict: Runtime Error):
#!/usr/bin/env python3
# -*- coding: utf-8 -*-
# D-Grid and Integers

from collections import defaultdict

def ReadInput():
	return [int(i) for i in input().split(" ")]

(R, C) = ReadInput()
N = int(input())
VectorSet = set() 
Grid = defaultdict(list)
for i in range(N):
	(r, c, a) = ReadInput()
	Grid[("R", r)].append((("C", c), a))
	Grid[("C", c)].append((("R", r), a))
	VectorSet.add(('R', r))
	VectorSet.add(('C', c))

def iteration(vector):
	VectorSet.discard(vector)
	for (v, a) in Grid[vector]:
		temp = a - VectorCover[vector]
		if (v in VectorCover):
			if(temp is not VectorCover[v]):
				print("No")
				exit()
		else:
			VectorCover[v] = temp
			iteration(v) 

while(len(VectorSet) is not 0):
	vector = VectorSet.pop()
	VectorCover = defaultdict(int)
	VectorCover[vector] = 0
	iteration(vector)
	minR = min(a for (p, a) in VectorCover.items() if (p[0] is "R"))
	minC = min(a for (p, a) in VectorCover.items() if (p[0] is "C"))
	if (minR + minC < 0):
		print("No")
		exit()
		
print("Yes")

Buggy submission (verdict: Runtime Error):
from collections import defaultdict
import copy

def readInput():
	return [int(i) for i in input().split(" ")]

(R, C) = readInput()
N = int(input())
rowIdx = set() 
cover = set()
grid = defaultdict(lambda:None)
rowGrid = defaultdict(set)
for i in range(N):
	(r, c, a) = readInput()
	r -= 1
	c -= 1
	rowGrid[r].add(c)
	grid[(r, c)] = a 
	rowIdx.add(r)

pairIdx = copy.copy(rowIdx)	
for i in rowIdx:
	tempRow = rowGrid[i]
	tempRow.difference_update(cover)
	if (len(tempRow) is 0):
		continue
	pairIdx.remove(i)
	for j in pairIdx:
		tempPair = rowGrid[j]
		mark = 1
		for k in tempRow:
			if (grid[(j, k)] is now None):
				diff = grid[(i, k)] - grid[(j, k)]
				mark = 0 
				break
		if (mark is 1):
			continue
		for m in tempRow:
			anchor = grid[(i, m)]
			anchorP = grid[(j, m)]
			if (anchorP is None and anchor < diff):
				print('No')
				exit()
			elif (anchorP is not None and anchor - anchorP != diff):
				print('No')
				exit()
		for n in tempPair:
			anchor = grid[(j, n)]
			anchorP = grid[(i, n)]
			if (anchorP is None and anchor < -diff):
				print('No')
				exit()
	cover &= tempRow
	if (len(cover) is C):
		break
print('Yes')

Buggy submission (verdict: Runtime Error):
from collections import defaultdict

def readInput():
	return [int(i) for i in input().split(" ")]

(R, C) = readInput()
N = int(input())
rowIdx = set() 
grid = defaultdict(lambda:None)
rowGrid = defaultdict(set)
for i in range(N):
	(r, c, a) = readInput()
	r -= 1
	c -= 1
	rowGrid[r].add(c)
	grid[(r, c)] = a 
	rowIdx.add(r)

pairIdx = rowIdx.copy	
for i in rowIdx:
	pairIdx.remove(i)
	for j in pairIdx:
		tempRow = rowGrid[i]
		tempPair = rowGrid[j]
		mark = 1
		for k in tempRow:
			if (grid[(j, k)] != None):
				diff = grid[(i, k)] - grid[(j, k)]
				mark = 0 
		if (mark is 1):
			continue
		for m in tempRow:
			anchor = grid[(i, m)]
			anchorP = grid[(j, m)]
			if (anchorP is None and anchor < diff):
				print('No')
				exit()
			elif (anchorP is not None and anchor - anchorP != diff):
				print('No')
				exit()
		for n in tempPair:
			anchor = grid[(j, n)]
			anchorP = grid[(i, n)]
			if (anchorP is None and anchor < -diff):
				print('No')
				exit()
print('Yes')

Buggy submission (verdict: Runtime Error):
#/usr/bin/env python3
# -*- coding: utf-8 -*-
# D-Grid and Integers

from collections import defaultdict

def readInput():
	return [int(i) for i in input().split(" ")]

(R, C) = readInput()
N = int(input())
rowIdx = list() 
colIdx = list()
grid = defaultdict(lambda:None)
rowGrid = defaultdict(list)
for i in range(N):
	(r, c, a) = readInput()
	r -= 1
	c -= 1
	rowGrid[r].append(c)
	grid[(r, c)] = a 
	rowIdx.append(r)

pairIdx = rowIdx.copy()	
for i in rowIdx:
	pairIdx.remove(i)
	for j in pairIdx:
		tempRow = rowGrid[i]
		tempPair = rowGrid[j]
		mark = 1
		for k in tempRow:
			if (grid[(j, k)] != None):
				diff = grid[(i, k)] - grid[(j, k)]
				mark = 0 
		if (mark  == 1):
			continue
		for m in tempRow:
			anchor = grid[(i, m)]
			anchorP = grid[(j, m)]
			if (anchorP == None and anchor < diff):
				print('No')
				exit()
			elif (anchorP != None and anchor - anchorP != diff):
				print('No')
				exit()
		for n in tempPair:
			anchor = grid[(j, n)]
			anchorP = grid[(i, n)]
			if (anchorP == None and anchor < -diff):
				print('No')
				exit()
print('Yes')