# [Solved] Given a string s containing just the characters ‘(‘, ‘)’, ‘{‘, ‘}’, ‘[‘ and ‘]’, determine if the input string is valid. ## Question

Given a string `s` containing just the characters `'('``')'``'{'``'}'``'['` and `']'`, determine if the input string is valid.

An input string is valid if:

1. Open brackets must be closed by the same type of brackets.
2. Open brackets must be closed in the correct order.
3. 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 `'()[]{}'`.

## Python Solution

```class Solution:
def isValid(self, s: str) -> bool:
stack=[]
boo = True

for ch in s:
if ch in '([{':
stack.append(ch)
elif ch in ')]}':
try:
popped_element = stack.pop()
except:
boo=False
break
if popped_element=='(' and ch==')':
pass
elif popped_element=='{' and ch=='}':
pass
elif popped_element=='[' and ch==']':
pass
else:
boo=False
break
if len(stack)==0:
return (boo)
else:
return (False)```
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