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:

function solution(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 JavaScript

Time spent on task 37 minutes

Notes

not defined yet

Code: 02:00:37 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: 02:04:30 UTC, js, autosave

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// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');

function solution(S) {
    // write your code in JavaScript (Node.js 8.9.4)
}

Code: 02:04:40 UTC, js, autosave

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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] === ')' ) {
                 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] === ')' ) {
                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 === ')')  {
        return true
    }
    else {
        return false
    }
}

Code: 02:04:40 UTC, js, verify, result: Passed

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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] === ')' ) {
                 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] === ')' ) {
                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 === ')')  {
        return true
    }
    else {
        return false
    }
}

Analysis

expand all Example tests

▶

example1
example test

✔

0.072 s

▶

example2
example test2

✔

0.072 s

Code: 02:04:44 UTC, js, verify, result: Passed

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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] === ')' ) {
                 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] === ')' ) {
                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 === ')')  {
        return true
    }
    else {
        return false
    }
}

Analysis

expand all Example tests

▶

example1
example test

✔

0.072 s

▶

example2
example test2

✔

0.072 s

Code: 02:36:33 UTC, js, verify, result: Passed

show code in pop-up

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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] === ')' ) {
                 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] === ')' ) {
                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 === ')')  {
        return true
    }
    else {
        return false
    }
}

Analysis

expand all Example tests

▶

example1
example test

✔

0.072 s

▶

example2
example test2

✔

0.072 s

Code: 02:36:36 UTC, js, final, score: 100

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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] === ')' ) {
                 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] === ')' ) {
                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 === ')')  {
        return true
    }
    else {
        return false
    }
}

Analysis summary

The solution obtained perfect score.

Analysis

Detected time complexity:

O(N)

expand all Example tests

▶

example1
example test

✔

0.072 s

▶

example2
example test2

✔

0.068 s

expand all Correctness tests

▶

negative_match
invalid structure, but the number of parentheses matches

✔

0.068 s

▶

empty
empty string

✔

0.068 s

▶

simple_grouped
simple grouped positive and negative test, length=22

✔

0.068 s

▶

small_random

✔

0.072 s

0.068 s

expand all Performance tests

▶

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

✔

0.076 s

0.068 s

▶

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

✔

0.104 s

0.068 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+

✔

0.076 s

0.068 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

✔

0.092 s

0.068 s