Update valid_parentheses.go

Author: Sandy

valid_parentheses/valid_parentheses.go

@@ -1,49 +1,26 @@
 package valid_parentheses
 
 func isValid(s string) bool {
-if len(s)%2 != 0 {
-return false
-}
-left := map[byte]struct{}{
-'(': struct{}{},
-'[': struct{}{},
-'{': struct{}{},
-}
-right := map[byte]struct{}{
-')': struct{}{},
-']': struct{}{},
-'}': struct{}{},
-}
-bytes := []byte(s)
-stack := []byte{}
-for i := range bytes {
-if _, ok := left[bytes[i]]; ok {
-stack = append(stack, bytes[i])
-} else if _, ok = right[bytes[i]]; ok {
-if len(stack) == 0 {
-return false
-}
-switch stack[len(stack)-1] {
-case '(':
-if bytes[i] != ')' {
-return false
-}
-case '[':
-if bytes[i] != ']' {
-return false
-}
-case '{':
-if bytes[i] != '}' {
-return false
-}
-}
-stack = stack[:len(stack)-1]
-} else {
-return false
-}
-}
-if len(stack) == 0 {
-return true
-}
-return false
+ m := map[rune]rune{
+ '(': ')',
+ '[': ']',
+ '{': '}',
+ }
+ stack := make([]rune, len(s))
+ top := 0
+ for _, c := range s {
+ switch c {
+ case '(', '[', '{':
+ stack[top] = m[c]
+ top++
+ case ')', ']', '}':
+ if top > 0 && stack[top-1] == c {
+ top--
+ } else {
+ return false
+ }
+ }
+ }
+
+ return top == 0
 }