package stack

import java.util.Stack


/*
*
*
* A string S consisting of N characters is considered to be properly nested if any of the following conditions is true:

S is empty;
S has the form "(U)" or "[U]" or "{U}" where U is a properly nested string;
S has the form "VW" where V and W are properly nested strings.
For example, the string "{[()()]}" is properly nested but "([)()]" is not.

Write a function:

fun solution(S: String): Int

that, given a string S consisting of N characters, returns 1 if S is properly nested and 0 otherwise.

For example, given S = "{[()()]}", the function should return 1 and given S = "([)()]", the function should return 0, as explained above.

Write an efficient algorithm for the following assumptions:

N is an integer within the range [0..200,000];
string S consists only of the following characters: "(", "{", "[", "]", "}" and/or ")".
*
*
*
*
* */

fun main(){
    println(solution("(]VW"))
}


fun solution(S: String): Int {
    // write your code in Kotlin 1.3.11 (Linux)
    // Space complexity O(n), Time complexity O(n)
    if (S.isEmpty()) return 1

    val stack = Stack<Char>()
    for (char in S){
        when(char){
            '{' -> stack.push(char)
            '(' -> stack.push(char)
            '[' -> stack.push(char)
            ']' -> {
                if (stack.isEmpty()) return 0
                if (stack.pop() != '['){
                    return 0
                }
            }
            ')' -> {
                if (stack.isEmpty()) return 0
                if (stack.pop() != '('){
                    return 0
                }
            }
            '}' -> {
                if (stack.isEmpty()) return 0
                if (stack.pop() != '{'){
                    return 0
                }
            }
        }
    }
    return if (stack.isEmpty()) 1 else 0
}
