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valid_parentheses.py
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valid_parentheses.py
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from sys import stdin
def inp():
return stdin.readline().rstrip()
def iinp():
return int(inp())
def mp():
return map(int, inp().split())
def liinp():
return list(mp())
def is_valid_bracket_naive(bracket):
close_bracket = ')]}'
if len(bracket)==1 or bracket[0] in close_bracket:
return False
brack1 = '()'
brack2 = "{}"
brack3 = '[]'
dp = [False for _ in range(len(bracket))]
for i in range(len(bracket)):
curr = bracket[i]
bra_open_close = []
open_b = ''
close_b = ''
opn = clos = 0
if curr in close_bracket:
close_b = str(curr)
clos = i
for bra in [brack1, brack2, brack3]:
if close_b in bra:
bra_open_close = bra
break
for j in range(i-1, -1, -1):
if dp[j]==False:
open_b = str(bracket[j])
opn = j
break
# print(open_b, close_b)
if open_b==bra_open_close[0] and close_b==bra_open_close[1]:
dp[opn] = dp[clos] = True
else:
return False
# print(dp)
return False if False in dp else True
def is_valid_bracket(bracket):
close_bracket = ')}]'
open_bracket = '({['
if len(bracket)==1 or len(bracket)%2!=0 or \
bracket[0] in close_bracket or bracket[-1] in open_bracket:
return False
stack = []
for i in range(len(bracket)-1, -1, -1):
current = bracket[i]
if current in open_bracket:
if stack:
if close_bracket.index(stack.pop())==open_bracket.index(current):
continue
else:
return False
else:
if current in open_bracket:
return False
stack.append(current)
return False if stack else True
if __name__ == "__main__":
bracket = inp()
print(is_valid_bracket(bracket))