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 21

Time spent on task 10 minutes

Notes

not defined yet

Code: 10:12:06 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) {
        // Implement your solution here
    }
}

Code: 10:12:07 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) {
        // Implement your solution here
    }
}

Code: 10:12:17 UTC, swift4, autosave

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import Foundation
import Glibc

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

public func solution(_ S : inout String) -> Int {
    // Implement your solution here
}

Code: 10:21:12 UTC, swift4, autosave

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import Foundation
import Glibc

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

public func solution(_ S : inout String) -> Int {
    var stack: [Character] = []
    
    for i in S {
        if i == "(" {
            stack.append(i)
        } else {
            if stack.isEmpty {
                return 0
            } else {
                stack.popLast()
            }
        }
    }
    
    return stack.isEmpty ? 1 : 0
}

Code: 10:21:13 UTC, swift4, verify, result: Passed

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import Foundation
import Glibc

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

public func solution(_ S : inout String) -> Int {
    var stack: [Character] = []
    
    for i in S {
        if i == "(" {
            stack.append(i)
        } else {
            if stack.isEmpty {
                return 0
            } else {
                stack.popLast()
            }
        }
    }
    
    return stack.isEmpty ? 1 : 0
}

Analysis

expand all Example tests

▶

example1
example test

✔

0.012 s

▶

example2
example test2

✔

0.012 s

Code: 10:21:22 UTC, swift4, 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

import Foundation
import Glibc

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

public func solution(_ S : inout String) -> Int {
    var stack: [Character] = []
    
    for i in S {
        if i == "(" {
            stack.append(i)
        } else {
            if stack.isEmpty {
                return 0
            } else {
                stack.popLast()
            }
        }
    }
    
    return stack.isEmpty ? 1 : 0
}

Analysis

expand all Example tests

▶

example1
example test

✔

0.012 s

▶

example2
example test2

✔

0.012 s

Code: 10:21:29 UTC, swift4, 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

import Foundation
import Glibc

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

public func solution(_ S : inout String) -> Int {
    var stack: [Character] = []
    
    for i in S {
        if i == "(" {
            stack.append(i)
        } else {
            if stack.isEmpty {
                return 0
            } else {
                stack.popLast()
            }
        }
    }
    
    return stack.isEmpty ? 1 : 0
}

Analysis summary

The solution obtained perfect score.

Analysis

Detected time complexity:

O(N)

expand all Example tests

▶

example1
example test

✔

0.012 s

▶

example2
example test2

✔

0.008 s

expand all Correctness tests

▶

negative_match
invalid structure, but the number of parentheses matches

✔

0.008 s

▶

empty
empty string

✔

0.008 s

▶

simple_grouped
simple grouped positive and negative test, length=22

✔

0.008 s

▶

small_random

✔

0.008 s

expand all Performance tests

▶

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

✔

0.012 s

0.008 s

▶

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

✔

0.036 s

0.012 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+

✔

0.016 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

✔

0.152 s

0.008 s