Codility/Brackets.java at master · madhurir23/Codility · GitHub

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/*
Determine whether a given string of parentheses (multiple types) is properly nested.
*/
import java.util.*;
class Solution {
    public int solution(String S) {
        Stack<Character> stack = new Stack<>();

        for (char ch:S.toCharArray()) {
            if (ch == '{' || ch == '(' || ch == '[') {
                stack.push(ch);
            } else {
                if (stack.isEmpty()) return 0;
                char stackTop = stack.peek();
                if (ch == '}' && stackTop != '{') return 0;
                if (ch == ']' && stackTop != '[') return 0;
                if (ch == ')' && stackTop != '(') return 0;
                stack.pop();
            }
        }
        return stack.isEmpty() ? 1 : 0;
    }
}