Test results - Codility

Tasks Details

easy

1. Brackets

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

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:

function solution(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 JavaScript

Time spent on task 1 minutes

Notes

not defined yet

Task timeline

Code: 02:00:37 UTC, js, 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 33 34 35 36 37 38 39 40 41 42

function solution(S) {
    // write your code in JavaScript (Node.js 8.9.4)
    let progress = true
    let index = 0
    let stack = []
    let error = false
    while (index < S.length) {
        if (stack.length === 0) {
            if (S[index] === ')' || S[index] === ']' || S[index] === '}') {
                 return 0
            } else {
            stack.push(S[index])
            }
        }
        else if (is_properly_nested(stack[stack.length-1],S[index])) {
            stack.pop(stack[stack.length-1])
        } else {
            if (S[index] === ')' || S[index] === ']' || S[index] === '}') {
                return 0
            }
            else {
                stack.push(S[index])
            }
        }
        index ++
    }

    if (stack.length === 0) {
        return 1
    } else {
        return 0
    }
}

function is_properly_nested(a,b){
    if ( (a === '(' && b === ')') || (a === '[' && b === ']') || (a === '{' && b === '}')) {
        return true
    }
    else {
        return false
    }
}

Analysis

▶

example1
example test 1

✔

▶

example2
example test 2

✔

Code: 02:00:41 UTC, js, 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 33 34 35 36 37 38 39 40 41 42

function solution(S) {
    // write your code in JavaScript (Node.js 8.9.4)
    let progress = true
    let index = 0
    let stack = []
    let error = false
    while (index < S.length) {
        if (stack.length === 0) {
            if (S[index] === ')' || S[index] === ']' || S[index] === '}') {
                 return 0
            } else {
            stack.push(S[index])
            }
        }
        else if (is_properly_nested(stack[stack.length-1],S[index])) {
            stack.pop(stack[stack.length-1])
        } else {
            if (S[index] === ')' || S[index] === ']' || S[index] === '}') {
                return 0
            }
            else {
                stack.push(S[index])
            }
        }
        index ++
    }

    if (stack.length === 0) {
        return 1
    } else {
        return 0
    }
}

function is_properly_nested(a,b){
    if ( (a === '(' && b === ')') || (a === '[' && b === ']') || (a === '{' && b === '}')) {
        return true
    }
    else {
        return false
    }
}

Analysis

▶

example1
example test 1

✔

▶

example2
example test 2

✔

Code: 02:00:44 UTC, js, final, score: 100

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 33 34 35 36 37 38 39 40 41 42

function solution(S) {
    // write your code in JavaScript (Node.js 8.9.4)
    let progress = true
    let index = 0
    let stack = []
    let error = false
    while (index < S.length) {
        if (stack.length === 0) {
            if (S[index] === ')' || S[index] === ']' || S[index] === '}') {
                 return 0
            } else {
            stack.push(S[index])
            }
        }
        else if (is_properly_nested(stack[stack.length-1],S[index])) {
            stack.pop(stack[stack.length-1])
        } else {
            if (S[index] === ')' || S[index] === ']' || S[index] === '}') {
                return 0
            }
            else {
                stack.push(S[index])
            }
        }
        index ++
    }

    if (stack.length === 0) {
        return 1
    } else {
        return 0
    }
}

function is_properly_nested(a,b){
    if ( (a === '(' && b === ')') || (a === '[' && b === ']') || (a === '{' && b === '}')) {
        return true
    }
    else {
        return false
    }
}

Analysis summary

The solution obtained perfect score.

Analysis

Detected time complexity:

O(N)

▶

example1
example test 1

✔

▶

example2
example test 2

✔

▶

negative_match
invalid structures

✔

▶

empty
empty string

✔

▶

simple_grouped
simple grouped positive and negative test, length=22

✔

▶

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

✔

▶

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

✔

▶

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 some brackets 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=120K+

✔