Test results - Codility

Tasks Details

easy

1. Nesting

Determine whether a given string of parentheses (single type) is properly nested.

75%

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:

class Solution { public int solution(String 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.

Write an efficient algorithm for the following assumptions:

N is an integer within the range [0..1,000,000];

string S is made only of the characters '(' and/or ')'.

Solution

Programming language used Java 8

Time spent on task 1 minutes

Notes

not defined yet

Task timeline

Code: 12:51:40 UTC, java, verify, result: Passed

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32

// you can also use imports, for example:
// import java.util.*;

// you can write to stdout for debugging purposes, e.g.
// System.out.println("this is a debug message");

class Solution {
    public int solution(String S) {
       char[] charArr = S.toCharArray();
        int checkNested = 0;
        int result = 1;

        if((S.length() == 0) || charArr.length == 0) {
            return 1;
        }
        

        for(char tempchar : charArr) {
            if(tempchar == '(') {
                checkNested++;
            }
            else if(tempchar == ')') {
                checkNested--;
            }
            if(checkNested < 0 ) {
                result = 0;
            }
        }

        return result;
    }
}

Analysis

▶

example1
example test

✔

▶

example2
example test2

✔

Code: 12:51:46 UTC, java, verify, result: Passed

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32

// you can also use imports, for example:
// import java.util.*;

// you can write to stdout for debugging purposes, e.g.
// System.out.println("this is a debug message");

class Solution {
    public int solution(String S) {
       char[] charArr = S.toCharArray();
        int checkNested = 0;
        int result = 1;

        if((S.length() == 0) || charArr.length == 0) {
            return 1;
        }
        

        for(char tempchar : charArr) {
            if(tempchar == '(') {
                checkNested++;
            }
            else if(tempchar == ')') {
                checkNested--;
            }
            if(checkNested < 0 ) {
                result = 0;
            }
        }

        return result;
    }
}

Analysis

▶

example1
example test

✔

▶

example2
example test2

✔

Code: 12:51:50 UTC, java, final, score: 75

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32

// you can also use imports, for example:
// import java.util.*;

// you can write to stdout for debugging purposes, e.g.
// System.out.println("this is a debug message");

class Solution {
    public int solution(String S) {
       char[] charArr = S.toCharArray();
        int checkNested = 0;
        int result = 1;

        if((S.length() == 0) || charArr.length == 0) {
            return 1;
        }
        

        for(char tempchar : charArr) {
            if(tempchar == '(') {
                checkNested++;
            }
            else if(tempchar == ')') {
                checkNested--;
            }
            if(checkNested < 0 ) {
                result = 0;
            }
        }

        return result;
    }
}

Analysis summary

The following issues have been detected: wrong answers.

For example, for the input '()(()()(((()())(()()))' the solution returned a wrong answer (got 1 expected 0).

Analysis

▶

example1
example test

✔

▶

example2
example test2

✔

▶

negative_match
invalid structure, but the number of parentheses matches

✔

▶

empty
empty string

✔

▶

simple_grouped
simple grouped positive and negative test, length=22

✘

WRONG ANSWER
got 1 expected 0

▶

small_random

✔

▶

large1
simple large positive and negative test, 10K or 10K+1 ('s followed by 10K )'s

✘

WRONG ANSWER
got 1 expected 0

▶

large_full_ternary_tree
tree of the form T=(TTT) and depth 11, length=177K+

✔

▶

multiple_full_binary_trees
sequence of full trees of the form T=(TT), depths [1..10..1], with/without unmatched ')' at the end, length=49K+

✔

▶

broad_tree_with_deep_paths
string of the form (TTT...T) of 300 T's, each T being '(((...)))' nested 200-fold, length=1 million

✔