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validParen.java
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validParen.java
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public class Solution {
public boolean isValid(String s) {
boolean returnValue = true;
HashMap<String,String> map = new HashMap<String,String>();
if(s.length()==1) return false;
map.put("(",")");
map.put("[","]");
map.put("{","}");
Stack<String> stack = new Stack<String>();
/* for(int i = 0;i<s.length();i++){
String bracket = s.substring(i,i+1);
if(map.containsKey(bracket)){
stack.push(bracket);
}
else{
String openBracket="";
if(!stack.empty()){
openBracket = stack.pop();
}
else{
return false;
}
if(map.get(openBracket).compareTo(bracket)==0){
returnValue = true;
}
else{
returnValue = false;
}
}
}
if(!stack.empty()) return false;
return returnValue; */
for(int i=0;i<s.length();i++){
String bracket = s.substring(i,i+1);
if(map.containsKey(bracket)){
stack.push(bracket);
}
else{
if(stack.empty()) return false;
String top = stack.peek();
if(map.get(top).compareTo(bracket)==0){
stack.pop();
}
else{
return false;
}
}
}
if(stack.empty()){
return true;
}
else{
return false;
}
}
}