[Codility Lessons] Nesting(20/n)

[Lesson7] Stacks and Queues

Nesting

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Java Solution

import java.util.*;

class Solution {
    public int solution(String S) {
        if(S.length()%2 > 0){
            return 0;    
        }
        Stack<Character> left = new Stack<Character>();
        for(int i = 0; i < S.length(); i++){
            char str = S.charAt(i);
            if(str == '('){
                left.push(str);
            }else{
                if(left.empty()){
                    return 0;    
                }
                left.pop();
            }
        }
        if(!left.empty()){
            return 0;    
        }
        return 1;
    }
}

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PHP Solution

function solution($S) {
    if(strlen($S)%2 > 0){
        return 0;    
    }
    $left = array();
    for($i = 0; $i < strlen($S); $i++){
        $ch = $S{$i};
        if($ch == '('){
            array_push($left, $ch);    
        }else{
            if(count($left) == 0){
                return 0;    
            }
            array_pop($left);
        }
    }
    if(count($left) > 0){
        return 0;    
    }
    return 1;
}