423. Valid parentheses "Lintcode java"

Description

Given A string containing just the characters,, ‘(‘, ‘)‘ ‘{‘ , and ‘}‘ ‘[‘ ‘]‘ , determine if the input string is valid .

Example

The brackets must close in the correct order, and is all valid but and is not "()" "()[]{}" "(]" "([)]" .

Challenge

O (n) time, n is the number of parentheses

Problem solving: Parentheses matching problems, using stacks to do relatively simple, the code is as follows:

 Public classSolution {/**     * @params:a String *@return: Whether the string is a valid parentheses*/     Public Booleanisvalidparentheses (String s) {//Write your code hereStack<character>stack =NewStack<character>();  for(inti = 0; I < s.length (); i++){            if(S.charat (i) = = ' (' | | | S.charat (i) = = ' {' | | s.charat (i) = = ' [') {Stack.push (S.charat (i)); }Else{//before pop, check that the stack is empty.                if(!Stack.isempty ()) {                    Switch(S.charat (i)) { Case‘)‘:                        if(!stack.pop (). Equals (' (')){                            return false; }                         Break;  Case‘]‘:                        if(!stack.pop (). Equals (' [')){                            return false; }                         Break;  Case‘}‘:                        if(!stack.pop (). Equals (' {')){                            return false; }                         Break; }                }Else{                    return false; }            }        }        if(Stack.isempty ()) {return true; }Else{            return false; }    }}

423. Valid parentheses "Lintcode java"