Test results - Codility

Tasks Details

easy

1. Dominator

Find an index of an array such that its value occurs at more than half of indices in the array.

Task Score

100%

Correctness

100%

Performance

100%

Task description

An array A consisting of N integers is given. The dominator of array A is the value that occurs in more than half of the elements of A.

For example, consider array A such that

A[0] = 3 A[1] = 4 A[2] = 3 A[3] = 2 A[4] = 3 A[5] = -1 A[6] = 3 A[7] = 3

The dominator of A is 3 because it occurs in 5 out of 8 elements of A (namely in those with indices 0, 2, 4, 6 and 7) and 5 is more than a half of 8.

Write a function

def solution(A)

that, given an array A consisting of N integers, returns index of any element of array A in which the dominator of A occurs. The function should return −1 if array A does not have a dominator.

For example, given array A such that

A[0] = 3 A[1] = 4 A[2] = 3 A[3] = 2 A[4] = 3 A[5] = -1 A[6] = 3 A[7] = 3

the function may return 0, 2, 4, 6 or 7, as explained above.

Write an efficient algorithm for the following assumptions:

N is an integer within the range [0..100,000];

each element of array A is an integer within the range [−2,147,483,648..2,147,483,647].

Solution

Programming language used Python

Time spent on task 5 minutes

Notes

not defined yet

Task timeline

‌

Code: 18:08:38 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: 18:08:41 UTC, py, autosave

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

def solution(A):
    # write your code in Python 3.6
    pass

Code: 18:08:48 UTC, py, autosave

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

def solution(A):
    def solution(A):
    stack = []
    idx = -1
    size = 0
    for i in range(len(A)):
        if size == 0: 
            idx = i
        elif A[i] != A[idx]:
            size = size -1
        elif A[i] == A[idx]:
             size = size +1
       
    
    cnt = 0
    for a in A:
        if a == A[idx]: cnt = cnt +1

    if cnt > len(A)/2: 
        return idx
    else:
        return -1

Code: 18:09:20 UTC, py, verify, result: Failed

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

def solution(A):
    def solution(A):
    stack = []
    idx = -1
    size = 0
    for i in range(len(A)):
        if size == 0: 
            idx = i
        elif A[i] != A[idx]:
            size = size -1
        elif A[i] == A[idx]:
             size = size +1
       
    
    cnt = 0
    for a in A:
        if a == A[idx]: cnt = cnt +1

    if cnt > len(A)/2: 
        return idx
    else:
        return -1

User test case 1:

[2, 1, 1, 1, 3]

User test case 2:

[0, 0, 1, 1, 1]

Analysis

expand all Example tests

▶

example
example test

✘

RUNTIME ERROR
tested program terminated with exit code 1

0.036 s

RUNTIME ERROR, tested program terminated with exit code 1

stderr:

Traceback (most recent call last):
  File "exec.py", line 129, in <module>
    main()
  File "exec.py", line 70, in main
    sol = __import__('solution')
  File "/tmp/solution.py", line 6
    stack = []
        ^
IndentationError: expected an indented block

expand all User tests

▶

test_data1

✘

RUNTIME ERROR
tested program terminated with exit code 1

0.036 s

RUNTIME ERROR, tested program terminated with exit code 1

stderr:

Traceback (most recent call last):
  File "exec.py", line 129, in <module>
    main()
  File "exec.py", line 70, in main
    sol = __import__('solution')
  File "/tmp/solution.py", line 6
    stack = []
        ^
IndentationError: expected an indented block

▶

test_data2

✘

RUNTIME ERROR
tested program terminated with exit code 1

0.036 s

RUNTIME ERROR, tested program terminated with exit code 1

stderr:

Traceback (most recent call last):
  File "exec.py", line 129, in <module>
    main()
  File "exec.py", line 70, in main
    sol = __import__('solution')
  File "/tmp/solution.py", line 6
    stack = []
        ^
IndentationError: expected an indented block

Code: 18:09:30 UTC, py, autosave

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

def solution(A):

    idx = -1
    size = 0
    for i in range(len(A)):
        if size == 0: 
            idx = i
        elif A[i] != A[idx]:
            size = size -1
        elif A[i] == A[idx]:
             size = size +1
       
    
    cnt = 0
    for a in A:
        if a == A[idx]: cnt = cnt +1

    if cnt > len(A)/2: 
        return idx
    else:
        return -1

Code: 18:09:32 UTC, py, verify, result: Passed

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

def solution(A):
    idx = -1
    size = 0
    for i in range(len(A)):
        if size == 0: 
            idx = i
        elif A[i] != A[idx]:
            size = size -1
        elif A[i] == A[idx]:
             size = size +1
       
    
    cnt = 0
    for a in A:
        if a == A[idx]: cnt = cnt +1

    if cnt > len(A)/2: 
        return idx
    else:
        return -1

User test case 1:

[2, 1, 1, 1, 3]

User test case 2:

[0, 0, 1, 1, 1]

Analysis

expand all Example tests

▶

example
example test

✔

0.036 s

expand all User tests

▶

test_data1

✔

0.036 s

OK
function result: -1

▶

test_data2

✔

0.036 s

OK
function result: 4

Code: 18:10:00 UTC, py, verify, result: Passed

show code in pop-up

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

def solution(A):
    idx = -1
    size = 0
    for i in range(len(A)):
        if size == 0: 
            idx = i
        elif A[i] != A[idx]:
            size = size -1
        elif A[i] == A[idx]:
             size = size +1
       
    print(idx)
    cnt = 0
    for a in A:
        if a == A[idx]: cnt = cnt +1

    if cnt > len(A)/2: 
        return idx
    else:
        return -1

User test case 1:

[2, 1, 1, 1, 3]

User test case 2:

[0, 0, 1, 1, 1]

Analysis

expand all Example tests

▶

example
example test

✔

0.056 s

stdout:

expand all User tests

▶

test_data1

✔

0.052 s

OK
function result: -1

stdout:

▶

test_data2

✔

0.056 s

OK
function result: 4

stdout:

Code: 18:10:30 UTC, py, autosave

show code in pop-up

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

def solution(A):
    idx = -1
    size = 0
    for i in range(len(A)):
        
        if size == 0: 
            idx = i
        elif A[i] != A[idx]:
            size = size -1
        elif A[i] == A[idx]:
             size = size +1
       
    print(idx)
    cnt = 0
    for a in A:
        if a == A[idx]: cnt = cnt +1

    if cnt > len(A)/2: 
        return idx
    else:
        return -1

Code: 18:10:43 UTC, py, verify, result: Passed

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

def solution(A):
    idx = -1
    size = 0
    for i in range(len(A)):
        if size == 0: 
            idx = i
        elif A[i] != A[idx]:
            size = size -1
        elif A[i] == A[idx]:
             size = size +1
        print(idx,size)
       
    print(idx)
    cnt = 0
    for a in A:
        if a == A[idx]: cnt = cnt +1

    if cnt > len(A)/2: 
        return idx
    else:
        return -1

User test case 1:

[2, 1, 1, 1, 3]

User test case 2:

[0, 0, 1, 1, 1]

Analysis

expand all Example tests

▶

example
example test

✔

0.036 s

stdout:

expand all User tests

▶

test_data1

✔

0.036 s

OK
function result: -1

stdout:

▶

test_data2

✔

0.036 s

OK
function result: 4

stdout:

Code: 18:11:07 UTC, py, autosave

show code in pop-up

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

def solution(A):
    idx = -1
    size = 0
    for i in range(len(A)):
        if size == 0: 
            idx = i
        elif A[i] != A[idx]:
            size = size -1
        elif A[i] == A[idx]:
             size = size +1
        print(A[idx,size)
       
    print(idx)
    cnt = 0
    for a in A:
        if a == A[idx]: cnt = cnt +1

    if cnt > len(A)/2: 
        return idx
    else:
        return -1

Code: 18:11:10 UTC, py, verify, result: Passed

show code in pop-up

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

def solution(A):
    idx = -1
    size = 0
    for i in range(len(A)):
        if size == 0: 
            idx = i
        elif A[i] != A[idx]:
            size = size -1
        elif A[i] == A[idx]:
             size = size +1
        print(A[idx],size)
       
    print(idx)
    cnt = 0
    for a in A:
        if a == A[idx]: cnt = cnt +1

    if cnt > len(A)/2: 
        return idx
    else:
        return -1

User test case 1:

[2, 1, 1, 1, 3]

User test case 2:

[0, 0, 1, 1, 1]

Analysis

expand all Example tests

▶

example
example test

✔

0.036 s

stdout:

expand all User tests

▶

test_data1

✔

0.036 s

OK
function result: -1

stdout:

▶

test_data2

✔

0.036 s

OK
function result: 4

stdout:

Code: 18:11:37 UTC, py, autosave

show code in pop-up

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

def solution(A):
    idx = -1
    size = 0
    for i in range(len(A)):
        if size == 0: 
            idx = i
            size = 1
        elif A[i] != A[idx]:
            size = size -1
        elif A[i] == A[idx]:
             size = size +1
        print(A[idx],size)
       
    print(idx)
    cnt = 0
    for a in A:
        if a == A[idx]: cnt = cnt +1

    if cnt > len(A)/2: 
        return idx
    else:
        return -1

Code: 18:11:40 UTC, py, verify, result: Passed

show code in pop-up

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

def solution(A):
    idx = -1
    size = 0
    for i in range(len(A)):
        if size == 0: 
            idx = i
            size = 1
        elif A[i] != A[idx]:
            size = size -1
        elif A[i] == A[idx]:
             size = size +1
        print(A[idx],size)
       
    print(idx)
    cnt = 0
    for a in A:
        if a == A[idx]: cnt = cnt +1

    if cnt > len(A)/2: 
        return idx
    else:
        return -1

User test case 1:

[2, 1, 1, 1, 3]

User test case 2:

[0, 0, 1, 1, 1]

Analysis

expand all Example tests

▶

example
example test

✔

0.036 s

stdout:

expand all User tests

▶

test_data1

✔

0.036 s

OK
function result: 2

stdout:

▶

test_data2

✔

0.036 s

OK
function result: 4

stdout:

Code: 18:11:53 UTC, py, 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

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

def solution(A):
    idx = -1
    size = 0
    for i in range(len(A)):
        if size == 0: 
            idx = i
            size = 1
        elif A[i] != A[idx]:
            size = size -1
        elif A[i] == A[idx]:
             size = size +1

    cnt = 0
    for a in A:
        if a == A[idx]: cnt = cnt +1

    if cnt > len(A)/2: 
        return idx
    else:
        return -1

User test case 1:

[2, 1, 1, 1, 3]

User test case 2:

[0, 0, 1, 1, 1]

Analysis

expand all Example tests

▶

example
example test

✔

0.036 s

expand all User tests

▶

test_data1

✔

0.036 s

OK
function result: 2

▶

test_data2

✔

0.036 s

OK
function result: 4

Code: 18:12:11 UTC, py, autosave

show code in pop-up

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

def solution(A):
    idx = -1
    size = 0
    for i in range(len(A)):
        if size == 0: 
            idx = i
            size = 1
        elif A[i] != A[idx]:
            size = size - 1
        elif A[i] == A[idx]:
             size = size +1

    cnt = 0
    for a in A:
        if a == A[idx]: cnt = cnt +1

    if cnt > len(A)/2: 
        return idx
    else:
        return -1

Code: 18:12:39 UTC, py, 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

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

def solution(A):
    idx = -1
    size = 0
    for i in range(len(A)):
        if size == 0: 
            idx = i
            size = 1
        elif A[i] != A[idx]:
            size = size - 1
        elif A[i] == A[idx]:
             size = size +1

    cnt = 0
    for a in A:
        if a == A[idx]: cnt = cnt +1

    if cnt > len(A)/2: 
        return idx
    else:
        return -1

User test case 1:

[2, 1, 1, 1, 3]

User test case 2:

[0, 0, 1, 1, 1]

Analysis

expand all Example tests

▶

example
example test

✔

0.048 s

expand all User tests

▶

test_data1

✔

0.048 s

OK
function result: 2

▶

test_data2

✔

0.048 s

OK
function result: 4

Code: 18:12:42 UTC, py, final, score: 100

show code in pop-up

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

def solution(A):
    idx = -1
    size = 0
    for i in range(len(A)):
        if size == 0: 
            idx = i
            size = 1
        elif A[i] != A[idx]:
            size = size - 1
        elif A[i] == A[idx]:
             size = size +1

    cnt = 0
    for a in A:
        if a == A[idx]: cnt = cnt +1

    if cnt > len(A)/2: 
        return idx
    else:
        return -1

Analysis summary

The solution obtained perfect score.

Analysis

Detected time complexity:

O(N*log(N)) or O(N)

expand all Example tests

▶

example
example test

✔

0.036 s

expand all Correctness tests

▶

small_nondominator
all different and all the same elements

✔

0.036 s

▶

small_half_positions
half elements the same, and half + 1 elements the same

✔

0.036 s

▶

small
small test

✔

0.036 s

▶

small_pyramid
decreasing and plateau, small

✔

0.036 s

▶

extreme_empty_and_single_item
empty and single element arrays

✔

0.036 s

▶

extreme_half1
array with exactly N/2 values 1, N even + [0,0,1,1,1]

✔

0.036 s

▶

extreme_half2
array with exactly floor(N/2) values 1, N odd + [0,0,1,1,1]

✔

0.036 s

▶

extreme_half3
array with exactly ceil(N/2) values 1 + [0,0,1,1,1]

✔

0.036 s

expand all Performance tests

▶

medium_pyramid
decreasing and plateau, medium

✔

0.048 s

▶

large_pyramid
decreasing and plateau, large

✔

0.164 s

▶

medium_random
random test with dominator, N = 10,000

✔

0.048 s

▶

large_random
random test with dominator, N = 100,000

✔

0.172 s