Test results - Codility

Tasks Details

easy

1. CountTriangles

Count the number of triangles that can be built from a given set of edges.

Task Score

100%

Correctness

100%

Performance

100%

An array A consisting of N integers is given. A triplet (P, Q, R) is triangular if it is possible to build a triangle with sides of lengths A[P], A[Q] and A[R]. In other words, triplet (P, Q, R) is triangular if 0 ≤ P < Q < R < N and:

A[P] + A[Q] > A[R],

A[Q] + A[R] > A[P],

A[R] + A[P] > A[Q].

For example, consider array A such that:

A[0] = 10 A[1] = 2 A[2] = 5 A[3] = 1 A[4] = 8 A[5] = 12

There are four triangular triplets that can be constructed from elements of this array, namely (0, 2, 4), (0, 2, 5), (0, 4, 5), and (2, 4, 5).

Write a function:

function solution(A);

that, given an array A consisting of N integers, returns the number of triangular triplets in this array.

For example, given array A such that:

A[0] = 10 A[1] = 2 A[2] = 5 A[3] = 1 A[4] = 8 A[5] = 12

the function should return 4, as explained above.

Write an efficient algorithm for the following assumptions:

N is an integer within the range [0..1,000];

each element of array A is an integer within the range [1..1,000,000,000].

Solution

Programming language used JavaScript

Time spent on task 14 minutes

Notes

not defined yet

Code: 18:09:24 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(int[] A) {
        // write your code in Java SE 8
    }
}

Code: 18:09:24 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(int[] A) {
        // write your code in Java SE 8
    }
}

Code: 18:09:35 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(A) {
    // write your code in JavaScript (Node.js 8.9.4)
}

Code: 18:16:55 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(A) {
   
}

Code: 18:17:16 UTC, js, verify, result: Failed

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

function solution(A) {
    const N = A.length;

    A.sort((a, b) => a - b);

    console.log(A);
}

Analysis

expand all Example tests

▶

example
example, positive answer, length=6

✘

RUNTIME ERROR
tested program terminated with exit code 1

0.076 s

RUNTIME ERROR, tested program terminated with exit code 1

stderr:

Invalid result type, integer expected, 'undefined' found
Perhaps you are missing a 'return'?

stdout:

[ 1, 2, 5, 8, 10, 12 ]

Code: 18:17:25 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(A) {
    const N = A.length;

    A.sort((a, b) => a - b);

    for (let i = 0; i < )
}

Code: 18:17:56 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(A) {
    const N = A.length;

    A.sort((a, b) => a - b);

    for (let i = 0; i < N; i++) {
        let left = i + 1;
        let right = i + 2;

        while (true) {
            if ()
        }
    }
}

Code: 18:18:36 UTC, js, autosave

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

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

function solution(A) {
    const N = A.length;

    A.sort((a, b) => a - b);

    for (let i = 0; i < N; i++) {
        let left = i + 1;
        let right = i + 2;

        while (true) {
            if (k <)
        }
    }
}

Code: 18:18:49 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(A) {
    const N = A.length;

    A.sort((a, b) => a - b);

    for (let i = 0; i < N; i++) {
        let left = i + 1;
        let right = i + 2;

        while (true) {
            if (right < N && right)
        }
    }
}

Code: 18:19:08 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(A) {
    const N = A.length;

    A.sort((a, b) => a - b);

    for (let i = 0; i < N; i++) {
        let left = i + 1;
        let right = i + 2;

        while (true) {
            if (right < N && A[i] + A[left] > right)
        }
    }
}

Code: 18:19:35 UTC, js, autosave

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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

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

function solution(A) {
    const N = A.length;

    A.sort((a, b) => a - b);

    for (let i = 0; i < N; i++) {
        let left = i + 1;
        let right = i + 2;

        while (true) {
            if (right < N && A[i] + A[left] > A[right]) {
                right++;
            } else {
                
            }
        }
    }
}

Code: 18:20:05 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(A) {
    const N = A.length;

    A.sort((a, b) => a - b);
    let count = 0;

    for (let i = 0; i < N; i++) {
        let left = i + 1;
        let right = i + 2;

        while (left < N - 1) {
            if (right < N && A[i] + A[left] > A[right]) {
                right++;
            } else {
                left++;
                count++;
            }
        }
    }
}

Code: 18:20:11 UTC, js, verify, result: Failed

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

function solution(A) {
    const N = A.length;

    A.sort((a, b) => a - b);
    let count = 0;

    for (let i = 0; i < N; i++) {
        let left = i + 1;
        let right = i + 2;

        while (left < N - 1) {
            if (right < N && A[i] + A[left] > A[right]) {
                right++;
            } else {
                left++;
                count++;
            }
        }
    }

    return count;
}

Analysis

expand all Example tests

▶

example
example, positive answer, length=6

✘

WRONG ANSWER
got 10 expected 4

0.072 s

WRONG ANSWER, got 10 expected 4

Code: 18:20:55 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(A) {
    const N = A.length;

    A.sort((a, b) => a - b);
    let count = 0;

    for (let i = 0; i < N; i++) {
        let left = i + 1;
        let right = i + 2;

        while (left < N - 1) {
            if (right < N && A[i] + A[left] > A[right]) {
                right++;
            } else {
                left++;
                count 
            }
        }
    }

    return count;
}

Code: 18:21:02 UTC, js, verify, result: Passed

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

function solution(A) {
    const N = A.length;

    A.sort((a, b) => a - b);
    let count = 0;

    for (let i = 0; i < N; i++) {
        let left = i + 1;
        let right = i + 2;

        while (left < N - 1) {
            if (right < N && A[i] + A[left] > A[right]) {
                right++;
            } else {
                left++;
                count += right - left;
            }
        }
    }

    return count;
}

Analysis

expand all Example tests

▶

example
example, positive answer, length=6

✔

0.088 s

Code: 18:21:27 UTC, js, autosave

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

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

function solution(A) {
    const N = A.length;

    A.sort((a, b) => a - b);
    let count = 0;

    for (let i = 0; i < N - 2; i++) {
        let left = i + 1;
        let right = i + 2;

        while (left < N - 1) {
            if (right < N && A[i] + A[left] > A[right]) {
                right++;
            } else {
                left++;
                count += right - left;
            }
        }
    }

    return count;
}

Code: 18:21:28 UTC, js, 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

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

function solution(A) {
    const N = A.length;

    A.sort((a, b) => a - b);
    let count = 0;

    for (let i = 0; i < N - 2; i++) {
        let left = i + 1;
        let right = i + 2;

        while (left < N - 1) {
            if (right < N && A[i] + A[left] > A[right]) {
                right++;
            } else {
                left++;
                count += right - left;
            }
        }
    }

    return count;
}

Analysis

expand all Example tests

▶

example
example, positive answer, length=6

✔

0.072 s

Code: 18:21:49 UTC, js, 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

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

function solution(A) {
    const N = A.length;

    A.sort((a, b) => a - b);
    let count = 0;

    for (let i = 0; i < N - 2; i++) {
        let left = i + 1;
        let right = i + 2;

        while (left < N - 1) {
            if (right < N && A[i] + A[left] > A[right]) {
                right++;
            } else {
                left++;
                count += right - left;
            }
        }
    }

    return count;
}

Analysis

expand all Example tests

▶

example
example, positive answer, length=6

✔

0.072 s

Code: 18:23:05 UTC, js, 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

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

function solution(A) {
    const N = A.length;

    A.sort((a, b) => a - b);
    let count = 0;

    for (let i = 0; i < N - 2; i++) {
        let left = i + 1;
        let right = i + 2;

        while (left < N - 1) {
            if (right < N && A[i] + A[left] > A[right]) {
                right++;
            } else {
                left++;
                count += right - left;
            }
        }
    }

    return count;
}

Analysis

expand all Example tests

▶

example
example, positive answer, length=6

✔

0.072 s

Code: 18:23:08 UTC, js, 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

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

function solution(A) {
    const N = A.length;

    A.sort((a, b) => a - b);
    let count = 0;

    for (let i = 0; i < N - 2; i++) {
        let left = i + 1;
        let right = i + 2;

        while (left < N - 1) {
            if (right < N && A[i] + A[left] > A[right]) {
                right++;
            } else {
                left++;
                count += right - left;
            }
        }
    }

    return count;
}

Analysis summary

The solution obtained perfect score.

Analysis

Detected time complexity:

O(N**2)

expand all Example tests

▶

example
example, positive answer, length=6

✔

0.072 s

expand all Correctness tests

▶

extreme_empty
empty sequence + [5,3,3]

✔

0.072 s

▶

extreme_single
1-element sequence + [5,3,3]

✔

0.072 s

▶

extreme_two_elems
2-element sequence + [5,3,3]

✔

0.072 s

▶

extreme_arith_overflow
overflow test, 3 MAXINTs + [5,3,3]

✔

0.072 s

0.068 s

▶

simple

✔

0.068 s

▶

medium1
chaotic sequence of values from [1..100K], length=30

✔

0.072 s

▶

medium2
chaotic sequence of values from [1..1K], length=50

✔

0.072 s

expand all Performance tests

▶

large
chaotic sequence with values from [1..10], length=200

✔

0.076 s

▶

large2
1 followed by an ascending sequence of ~1K elements from [1..2K]

✔

0.088 s

▶

large_random
chaotic sequence of values from [1..1M], length=1K

✔

0.088 s

▶

large_the_same
sequence of the same value value

✔

0.080 s