Merge pull request #4 from openset/patch-2

Update: valid_parentheses

Author: hitzzc

valid_parentheses/valid_parentheses.go

@@ -1,49 +1,26 @@
 package valid_parentheses
 
 funcisValid(sstring) bool {
-iflen(s)%2!=0 {
-returnfalse
- }
-left:=map[byte]struct{}{
-'(': struct{}{},
-'[': struct{}{},
-'{': struct{}{},
- }
-right:=map[byte]struct{}{
-')': struct{}{},
-']': struct{}{},
-'}': struct{}{},
- }
-bytes:= []byte(s)
-stack:= []byte{}
-fori:=rangebytes {
-if_, ok:=left[bytes[i]]; ok {
-stack=append(stack, bytes[i])
- } elseif_, ok=right[bytes[i]]; ok {
-iflen(stack) ==0 {
-returnfalse
- }
-switchstack[len(stack)-1] {
-case'(':
-ifbytes[i] !=')' {
-returnfalse
- }
-case'[':
-ifbytes[i] !=']' {
-returnfalse
- }
-case'{':
-ifbytes[i] !='}' {
-returnfalse
- }
- }
-stack=stack[:len(stack)-1]
- } else {
-returnfalse
- }
- }
-iflen(stack) ==0 {
-returntrue
- }
-returnfalse
+m:=map[rune]rune{
+'(': ')',
+'[': ']',
+'{': '}',
+ }
+stack:=make([]rune, len(s))
+top:=0
+for_, c:=ranges {
+switchc {
+case'(', '[', '{':
+stack[top] =m[c]
+top++
+case')', ']', '}':
+iftop>0&&stack[top-1] ==c {
+top--
+ } else {
+returnfalse
+ }
+ }
+ }
+
+returntop==0
 }