LeetCode/ValidParanthesis.java at master · Srinath-V-S/LeetCode · GitHub

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class Solution {

    // create a stack class

    static class Stack{

        int top = -1;
        char ch[] = new char[7002];


        public void push(char c){
            if(top==7001){

            }
            else{
                // adding character to the stack
                ch[++top] = c;
            }
        }

        public char pop(){
            if(top==-1){
             return '\0';
            }
            else{
                char element  = ch[top];
                top--;
                return element;
            }

        }

        public boolean isEmpty(){
            return (top==-1)?true:false;
        }
    }


    public static boolean matchingpair(char c1,char c2){
        if(c1 == '{' && c2=='}')
            return true;
        if(c1 == '(' && c2==')')
            return true;
        if(c1 == '[' && c2==']')
            return true;


        return false;
    }
    public boolean isValid(String s) {

        Stack stack = new Stack();
        for(int i=0;i<s.length();i++){
            if(s.charAt(i) == '{'|| s.charAt(i) == '['||s.charAt(i) == '(' ){
                stack.push(s.charAt(i));
            }


            if(s.charAt(i) == '}'|| s.charAt(i) == ']'||s.charAt(i) == ')' ){


                if(stack.isEmpty()){
                    return false;
                }


                else if(!matchingpair(stack.pop(),s.charAt(i))){
                    return false;
                }
            }


        }


        if(stack.isEmpty()){
           return true;
        }
        else{
            return false;
        }

    }
}