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valid_parentheses_20.py
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valid_parentheses_20.py
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"""
Given a string s containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid.
An input string is valid if:
Open brackets must be closed by the same type of brackets.
Open brackets must be closed in the correct order.
Every close bracket has a corresponding open bracket of the same type.
Example 1:
Input: s = "()"
Output: true
Example 2:
Input: s = "()[]{}"
Output: true
Example 3:
Input: s = "(]"
Output: false
Constraints:
1 <= s.length <= 104
s consists of parentheses only '()[]{}'.
"""
class Solution:
def isValid(self, s: str) -> bool:
dict_pairs = {
"(" : ")",
"[" : "]",
"{" : "}"
}
stack = []
for char in s:
if char in dict_pairs.keys():
stack.append(char)
else:
if len(stack) == 0:
return False
else:
top_element = stack.pop()
if dict_pairs.get(top_element) == char:
continue
else:
return False
return len(stack) == 0
if __name__ == '__main__':
solution = Solution()
assert solution.isValid("()") == True, "Error on test case 1"
assert solution.isValid("()[]{}") == True, "Error on test case 2"
assert solution.isValid("(]") == False, "Error on test case 3"
assert solution.isValid("([)]") == False, "Error on test case 4"
assert solution.isValid("{[]}") == True, "Error on test case 5"
print("All tests passed successfully.")