Test results - Codility

Tasks Details

easy

1. Brackets

Determine whether a given string of parentheses (multiple types) is properly nested.

Task Score

100%

Correctness

100%

Performance

100%

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:

class Solution { public int solution(String S); }

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 is made only of the following characters: '(', '{', '[', ']', '}' and/or ')'.

Solution

Programming language used Java 8

Time spent on task 80 minutes

Notes

not defined yet

Code: 09:25:20 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: 09:26:15 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 {
    // write your code in Swift 4.2.1 (Linux)
}

Code: 10:42:11 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 {
    // write your code in Swift 4.2.1 (Linux)
}

Code: 10:42:14 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 {
    if S.isEmpty { return 1 }
    if S.count == 1 { return 0 }
    
    var stack: [Character] = []
    
    for character in S {
        switch character {
        case "}":
            if !stack.isEmpty && stack.last == "{" {
                stack.popLast()
            } else {
                return 0
            }
        case "]":
            if !stack.isEmpty && stack.last == "[" {
                stack.popLast()
            } else {
                return 0
            }
        case ")":
            if !stack.isEmpty && stack.last == "(" {
                stack.popLast()
            } else {
                return 0
            }
        default:
            stack.append(character)
        }
    }
    
    return stack.count == 0 ? 1 : 0
}

Analysis

expand all Example tests

▶

example1
example test 1

✔

0.032 s

▶

example2
example test 2

✔

0.028 s

Code: 10:44:17 UTC, swift4, verify, result: Passed

show code in pop-up

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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 {
    if S.isEmpty { return 1 }
    if S.count == 1 { return 0 }
    
    var stack: [Character] = []
    
    for character in S {
        switch character {
        case "}":
            if !stack.isEmpty && stack.last == "{" {
                stack.popLast()
            } else {
                return 0
            }
        case "]":
            if !stack.isEmpty && stack.last == "[" {
                stack.popLast()
            } else {
                return 0
            }
        case ")":
            if !stack.isEmpty && stack.last == "(" {
                stack.popLast()
            } else {
                return 0
            }
        default:
            stack.append(character)
        }
    }
    
    return stack.count == 0 ? 1 : 0
}

Analysis

expand all Example tests

▶

example1
example test 1

✔

0.028 s

▶

example2
example test 2

✔

0.028 s

Code: 10:44:50 UTC, swift4, verify, result: Passed

show code in pop-up

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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 {
    if S.isEmpty { return 1 }
    if S.count == 1 { return 0 }
    
    var stack: [Character] = []
    
    for character in S {
        switch character {
        case "}":
            if !stack.isEmpty && stack.last == "{" {
                stack.popLast()
            } else {
                return 0
            }
        case "]":
            if !stack.isEmpty && stack.last == "[" {
                stack.popLast()
            } else {
                return 0
            }
        case ")":
            if !stack.isEmpty && stack.last == "(" {
                stack.popLast()
            } else {
                return 0
            }
        default:
            stack.append(character)
        }
    }
    
    return stack.count == 0 ? 1 : 0
}

Analysis

expand all Example tests

▶

example1
example test 1

✔

0.028 s

▶

example2
example test 2

✔

0.028 s

Code: 10:44:56 UTC, swift4, final, score: 100

show code in pop-up

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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 {
    if S.isEmpty { return 1 }
    if S.count == 1 { return 0 }
    
    var stack: [Character] = []
    
    for character in S {
        switch character {
        case "}":
            if !stack.isEmpty && stack.last == "{" {
                stack.popLast()
            } else {
                return 0
            }
        case "]":
            if !stack.isEmpty && stack.last == "[" {
                stack.popLast()
            } else {
                return 0
            }
        case ")":
            if !stack.isEmpty && stack.last == "(" {
                stack.popLast()
            } else {
                return 0
            }
        default:
            stack.append(character)
        }
    }
    
    return stack.count == 0 ? 1 : 0
}

Analysis summary

The solution obtained perfect score.

Analysis

Detected time complexity:

O(N)

expand all Example tests

▶

example1
example test 1

✔

0.028 s

▶

example2
example test 2

✔

0.028 s

expand all Correctness tests

▶

negative_match
invalid structures

✔

0.028 s

▶

empty
empty string

✔

0.028 s

▶

simple_grouped
simple grouped positive and negative test, length=22

✔

0.028 s

expand all Performance tests

▶

large1
simple large positive test, 100K ('s followed by 100K )'s + )(

✔

0.060 s

0.028 s

0.032 s

▶

large2
simple large negative test, 10K+1 ('s followed by 10K )'s + )( + ()

✔

0.032 s

0.028 s

▶

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

✔

0.056 s

▶

multiple_full_binary_trees
sequence of full trees of the form T=(TT), depths [1..10..1], with/without some brackets at the end, length=49K+

✔

0.036 s

▶

broad_tree_with_deep_paths
string of the form [TTT...T] of 300 T's, each T being '{{{...}}}' nested 200-fold, length=120K+

✔

0.048 s