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valid-parentheses-20.go
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valid-parentheses-20.go
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/*
20. Valid Parentheses
Easy
21.3K
1.4K
Companies
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 '()[]{}'.
*/
func isValid(s string) bool {
var openBrackets []rune
hasOpenParenthesis := 0
hasOpenBracket := 0
hasOpenCurlyBrace := 0
result := true
if len(s) % 2 != 0 {
return false
} else if len(s) == 0 {
return true
}
for _, value := range s {
if value == '(' || value == '[' || value == '{' {
openBrackets = append(openBrackets, value)
switch value {
case '(':
hasOpenParenthesis++
case '[':
hasOpenBracket++
case '{':
hasOpenCurlyBrace++
default:
break
}
} else {
if len(openBrackets) == 0 {
return false
}
lastValue := openBrackets[0]
lastIdx := len(openBrackets) - 1
if lastIdx >= 0 {
lastValue = openBrackets[lastIdx]
}
switch value {
case ')':
if lastValue != '(' {
return false
} else {
openBrackets = openBrackets[:len(openBrackets)-1]
hasOpenParenthesis--
}
case ']':
if lastValue != '[' {
return false
} else {
openBrackets = openBrackets[:len(openBrackets)-1]
hasOpenBracket--
}
case '}':
if lastValue != '{' {
return false
} else {
openBrackets = openBrackets[:len(openBrackets)-1]
hasOpenCurlyBrace--
}
default:
break
}
}
}
if hasOpenParenthesis > 0 || hasOpenBracket > 0 || hasOpenCurlyBrace > 0 {
result = false
}
return result
}
// Original solution
/*
hasOpenParenthesis := false
hasOpenBracket := false
hasOpenCurlyBrace := false
// Iterate through s string
for _, value := range s {
// Open bracket?
// Check if appropriate flag is true
// Yes - return false
// No - Set appropriate flag to true
// Closing bracket?
// Check if appropriate flag is true
// Yes - Set flag to false and continue
// No - return false
switch value {
case '(':
if hasOpenParenthesis || hasOpenBracket || hasOpenCurlyBrace {
return false
} else {
hasOpenParenthesis = true
}
case ')':
if hasOpenParenthesis && !hasOpenBracket && !hasOpenCurlyBrace {
hasOpenParenthesis = false
} else {
return false
}
case '[':
if hasOpenParenthesis || hasOpenBracket || hasOpenCurlyBrace {
return false
} else {
hasOpenBracket = true
}
case ']':
if !hasOpenParenthesis && hasOpenBracket && !hasOpenCurlyBrace {
hasOpenBracket = false
} else {
return false
}
case '{':
if hasOpenParenthesis || hasOpenBracket || hasOpenCurlyBrace {
return false
} else {
hasOpenCurlyBrace = true
}
case '}':
if !hasOpenParenthesis && !hasOpenBracket && hasOpenCurlyBrace {
hasOpenCurlyBrace = false
} else {
return false
}
default:
return false
}
*/