Nesting.md

Task description

A string S consisting of N characters is called properly nested if:

• S is empty;
• S has the form "(U)" where U is a properly nested string;
• S has the form "VW" where V and W are properly nested strings.

For example, string "(()(())())" is properly nested but string "())" isn't.

Write a function:

function solution(S);

that, given a string S consisting of N characters, returns 1 if string 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.

Assume that:

• N is an integer within the range [0..1,000,000];
• string S consists only of the characters "(" and/or ")".

Complexity:

• expected worst-case time complexity is O(N);
• expected worst-case space complexity is O(1) (not counting the storage required for input arguments).

function solution(S) {
    let counter = 0;
    
    for (var i = 0; i < S.length; i++) {
        switch(S[i]) {
            case "(":
                counter++;
                break;
                
            case ")":
                counter--;
                break;
        }
        
        if (counter < 0) return 0
    }
    
    return counter === 0 ? 1 : 0 
}