Test results - Codility

Tasks Details

easy

1. Nesting

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

Task Score

100%

Correctness

100%

Performance

100%

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 5 minutes

Notes

not defined yet

Task timeline

Code: 10:29:44 UTC, java, autosave

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// 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) {
        // write your code in Java SE 8
    }
}

Code: 10:29:50 UTC, java, autosave

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1 2 3 4 5 6 7 8 9 10 11

// 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) {
        // write your code in Java SE 8
    }
}

Code: 10:29:59 UTC, java, verify, result: Failed

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22

// 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) {
        // write your code in Java SE 8
        Stack<Character> stack = new Stack<>();
        char[] chars = S.toCharArray();

        for (char c : chars) {
            if (c == '(') {
                stack.push(c);
            } else if ((stack.empty() && c == ')') || (!stack.empty() && stack.pop() != '(')) {
                return 0;
            }
        }
        return 1;
    }
}

Analysis

Compile error

Solution.java:10: error: cannot find symbol
        Stack<Character> stack = new Stack<>();
        ^
  symbol:   class Stack
  location: class Solution
Solution.java:10: error: cannot find symbol
        Stack<Character> stack = new Stack<>();
                                     ^
  symbol:   class Stack
  location: class Solution
2 errors

Code: 10:30:07 UTC, java, autosave

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// 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) {
        // write your code in Java SE 8
        Stack<Character> stack = new Stack<>();
        char[] chars = S.toCharArray();

        for (char c : chars) {
            if (c == '(') {
                stack.push(c);
            } else if ((stack.empty() && c == ')') || (!stack.empty() && stack.pop() != '(')) {
                return 0;
            }
        }
        return 1;
    }
}

Code: 10:30:15 UTC, java, verify, result: Passed

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22

// 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) {
        // write your code in Java SE 8
        Stack<Character> stack = new Stack<>();
        char[] chars = S.toCharArray();

        for (char c : chars) {
            if (c == '(') {
                stack.push(c);
            } else if ((stack.empty() && c == ')') || (!stack.empty() && stack.pop() != '(')) {
                return 0;
            }
        }
        return 1;
    }
}

User test case 1:

['()(()()(((()())(()()))']

Analysis

expand all Example tests

▶

example1
example test

✔

0.008 s

▶

example2
example test2

✔

0.004 s

expand all User tests

▶

test_data1

✔

0.008 s

OK
function result: 1

Code: 10:33:23 UTC, java, autosave

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// 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) {
        // write your code in Java SE 8
        Stack<Character> stack = new Stack<>();
        char[] chars = S.toCharArray();

        for (char c : chars) {
            if (c == '(') {
                stack.push(c);
            } else if ((stack.empty() && c == ')') || (!stack.empty() && stack.pop() != '(')) {
                return 0;
            }
        }
        
        
        return 1;
    }
}

Code: 10:33:46 UTC, java, verify, result: Failed

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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

// 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) {
        // write your code in Java SE 8
        Stack<Character> stack = new Stack<>();
        char[] chars = S.toCharArray();

        for (char c : chars) {
            if (c == '(') {
                stack.push(c);
            } else if ((stack.empty() && c == ')') || (!stack.empty() && stack.pop() != '(')) {
                return 0;
            }
        }
        if(!stack.enpty()){
            return 0;
        }
        
        
        return 1;
    }
}

Analysis

Compile error

Solution.java:20: error: cannot find symbol
        if(!stack.enpty()){
                 ^
  symbol:   method enpty()
  location: variable stack of type Stack<Character>
1 error

Code: 10:33:53 UTC, java, verify, result: Passed

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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

// 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) {
        // write your code in Java SE 8
        Stack<Character> stack = new Stack<>();
        char[] chars = S.toCharArray();

        for (char c : chars) {
            if (c == '(') {
                stack.push(c);
            } else if ((stack.empty() && c == ')') || (!stack.empty() && stack.pop() != '(')) {
                return 0;
            }
        }
        if(!stack.empty()){
            return 0;
        }
        
        
        return 1;
    }
}

User test case 1:

['()(()()(((()())(()()))']

Analysis

expand all Example tests

▶

example1
example test

✔

0.004 s

▶

example2
example test2

✔

0.004 s

expand all User tests

▶

test_data1

✔

0.004 s

OK
function result: 0

Code: 10:33:58 UTC, java, verify, result: Passed

show code in pop-up

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

// 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) {
        // write your code in Java SE 8
        Stack<Character> stack = new Stack<>();
        char[] chars = S.toCharArray();

        for (char c : chars) {
            if (c == '(') {
                stack.push(c);
            } else if ((stack.empty() && c == ')') || (!stack.empty() && stack.pop() != '(')) {
                return 0;
            }
        }
        if(!stack.empty()){
            return 0;
        }
        
        
        return 1;
    }
}

User test case 1:

['()(()()(((()())(()()))']

Analysis

expand all Example tests

▶

example1
example test

✔

0.004 s

▶

example2
example test2

✔

0.008 s

expand all User tests

▶

test_data1

✔

0.008 s

OK
function result: 0

Code: 10:34:03 UTC, java, final, score: 100

show code in pop-up

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

// 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) {
        // write your code in Java SE 8
        Stack<Character> stack = new Stack<>();
        char[] chars = S.toCharArray();

        for (char c : chars) {
            if (c == '(') {
                stack.push(c);
            } else if ((stack.empty() && c == ')') || (!stack.empty() && stack.pop() != '(')) {
                return 0;
            }
        }
        if(!stack.empty()){
            return 0;
        }
        
        
        return 1;
    }
}

Analysis summary

The solution obtained perfect score.

Analysis

Detected time complexity:

O(N)

expand all Example tests

▶

example1
example test

✔

0.004 s

▶

example2
example test2

✔

0.004 s

expand all Correctness tests

▶

negative_match
invalid structure, but the number of parentheses matches

✔

0.004 s

▶

empty
empty string

✔

0.008 s

▶

simple_grouped
simple grouped positive and negative test, length=22

✔

0.004 s

▶

small_random

✔

0.004 s

expand all Performance tests

▶

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

✔

0.028 s

0.004 s

▶

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

✔

0.224 s

0.004 s

▶

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+

✔

0.068 s

0.008 s

▶

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

✔

1.228 s

0.008 s