Test results - Codility

Tasks Details

easy

1. PassingCars

Count the number of passing cars on the road.

Task Score

100%

Correctness

100%

Performance

100%

A non-empty array A consisting of N integers is given. The consecutive elements of array A represent consecutive cars on a road.

Array A contains only 0s and/or 1s:

0 represents a car traveling east,

1 represents a car traveling west.

The goal is to count passing cars. We say that a pair of cars (P, Q), where 0 ≤ P < Q < N, is passing when P is traveling to the east and Q is traveling to the west.

For example, consider array A such that:

A[0] = 0 A[1] = 1 A[2] = 0 A[3] = 1 A[4] = 1

We have five pairs of passing cars: (0, 1), (0, 3), (0, 4), (2, 3), (2, 4).

Write a function:

def solution(A)

that, given a non-empty array A of N integers, returns the number of pairs of passing cars.

The function should return −1 if the number of pairs of passing cars exceeds 1,000,000,000.

For example, given:

A[0] = 0 A[1] = 1 A[2] = 0 A[3] = 1 A[4] = 1

the function should return 5, as explained above.

Write an efficient algorithm for the following assumptions:

N is an integer within the range [1..100,000];

each element of array A is an integer that can have one of the following values: 0, 1.

Solution

Programming language used Python

Time spent on task 4 minutes

Notes

not defined yet

Code: 14:21:10 UTC, java, autosave

show code in pop-up

1 2 3 4 5 6 7 8 9 10 11

// 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: 14:21:15 UTC, pas, autosave

show code in pop-up

1 2 3 4 5 6 7

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

function solution(A: array of longint; N: longint): longint;
begin
    (* write your code in Free Pascal 3.0 *)
end;

Code: 14:21:18 UTC, py, autosave

show code in pop-up

1 2 3 4 5 6

# 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: 14:21:58 UTC, py, autosave

show code in pop-up

1 2 3 4 5 6 7 8

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

def solution(A):
    mult = 0 
    for a in A:
        if a == 0: mult = mult+1
        else:

Code: 14:22:09 UTC, py, autosave

show code in pop-up

1 2 3 4 5 6 7 8 9

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

def solution(A):
    mult = 0 
    summ = 0
    for a in A:
        if a == 0: mult = mult+1
        else:

Code: 14:22:24 UTC, py, autosave

show code in pop-up

1 2 3 4 5 6 7 8 9

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

def solution(A):
    mult = 0 
    summ = 0
    for a in A:
        if a == 0: mult = mult+1
        else: sum = sum + ()

Code: 14:22:35 UTC, py, autosave

show code in pop-up

1 2 3 4 5 6 7 8 9

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

def solution(A):
    mult = 0 
    summ = 0
    for a in A:
        if a == 0: mult = mult+1
        else: sum = sum + (1*mult)

Code: 14:23:05 UTC, py, autosave

show code in pop-up

1 2 3 4 5 6 7 8 9 10 11 12

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

def solution(A):
    east = 0 
    summ = 0
    for a in A:
        if a == 0: mult = east+1
        else: sum = sum + east
        
    print summ
    return summ

Code: 14:23:06 UTC, py, verify, result: Failed

show code in pop-up

1 2 3 4 5 6 7 8 9 10 11 12

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

def solution(A):
    east = 0 
    summ = 0
    for a in A:
        if a == 0: mult = east+1
        else: sum = sum + east
        
    print summ
    return summ

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 11
    print summ
             ^
SyntaxError: Missing parentheses in call to 'print'. Did you mean print(summ)?

Code: 14:23:16 UTC, py, verify, result: Failed

show code in pop-up

1 2 3 4 5 6 7 8 9 10 11 12

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

def solution(A):
    east = 0 
    summ = 0
    for a in A:
        if a == 0: mult = east+1
        else: sum = sum + east
        
    print(summ)
    return summ

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 91, in main
    result = solution( A )
  File "/tmp/solution.py", line 9, in solution
    else: sum = sum + east
UnboundLocalError: local variable 'sum' referenced before assignment

Code: 14:23:29 UTC, py, verify, result: Failed

show code in pop-up

1 2 3 4 5 6 7 8 9 10 11 12

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

def solution(A):
    east = 0 
    summ = 0
    for a in A:
        if a == 0: mult = east+1
        else: summ = sum + east
        
    print(summ)
    return summ

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 91, in main
    result = solution( A )
  File "/tmp/solution.py", line 9, in solution
    else: summ = sum + east
TypeError: unsupported operand type(s) for +: 'builtin_function_or_method' and 'int'

Code: 14:23:35 UTC, py, autosave

show code in pop-up

1 2 3 4 5 6 7 8 9 10 11 12

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

def solution(A):
    east = 0 
    summ = 0
    for a in A:
        if a == 0: mult = east+1
        else: summ = summ + east
        
    print(summ)
    return summ

Code: 14:23:36 UTC, py, verify, result: Failed

show code in pop-up

1 2 3 4 5 6 7 8 9 10 11 12

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

def solution(A):
    east = 0 
    summ = 0
    for a in A:
        if a == 0: mult = east+1
        else: summ = summ + east
        
    print(summ)
    return summ

Analysis

expand all Example tests

▶

example
example test

✘

WRONG ANSWER
got 0 expected 5

0.036 s

WRONG ANSWER, got 0 expected 5

stdout:

Code: 14:23:58 UTC, py, verify, result: Passed

show code in pop-up

1 2 3 4 5 6 7 8 9 10 11 12

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

def solution(A):
    east = 0 
    summ = 0
    for a in A:
        if a == 0: east = east+1
        else: summ = summ + east
        
    print(summ)
    return summ

Analysis

expand all Example tests

▶

example
example test

✔

0.036 s

stdout:

Code: 14:24:05 UTC, py, autosave

show code in pop-up

1 2 3 4 5 6 7 8 9 10 11

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

def solution(A):
    east = 0 
    summ = 0
    for a in A:
        if a == 0: east = east+1
        else: summ = summ + east
        
    return summ

Code: 14:24:35 UTC, py, autosave

show code in pop-up

1 2 3 4 5 6 7 8 9 10 11 12

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

def solution(A):
    east = 0 
    summ = 0
    for a in A:
        if a == 0: east = east+1
        else: summ = summ + east
        
    if summ > 1000000000: return -1
    return summ

Code: 14:24:47 UTC, py, autosave

show code in pop-up

1 2 3 4 5 6 7 8 9 10 11 12

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

def solution(A):
    east = 0 
    summ = 0
    for a in A:
        if a == 0: east = east+1
        else: summ = summ + east
    
    if summ > 1000000000: return -1
    return summ

Code: 14:24:51 UTC, py, verify, result: Passed

show code in pop-up

1 2 3 4 5 6 7 8 9 10 11 12

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

def solution(A):
    east = 0 
    summ = 0
    for a in A:
        if a == 0: east = east+1
        else: summ = summ + east
    
    if summ > 1000000000: return -1
    return summ

Analysis

expand all Example tests

▶

example
example test

✔

0.036 s

Code: 14:25:00 UTC, py, verify, result: Passed

show code in pop-up

1 2 3 4 5 6 7 8 9 10 11 12

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

def solution(A):
    east = 0 
    summ = 0
    for a in A:
        if a == 0: east = east+1
        else: summ = summ + east
    
    if summ > 1000000000: return -1
    return summ

Analysis

expand all Example tests

▶

example
example test

✔

0.036 s

Code: 14:25:02 UTC, py, final, score: 100

show code in pop-up

1 2 3 4 5 6 7 8 9 10 11 12

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

def solution(A):
    east = 0 
    summ = 0
    for a in A:
        if a == 0: east = east+1
        else: summ = summ + east
    
    if summ > 1000000000: return -1
    return summ

Analysis summary

The solution obtained perfect score.

Analysis

Detected time complexity:

O(N)

expand all Example tests

▶

example
example test

✔

0.036 s

expand all Correctness tests

▶

single
single element

✔

0.036 s

▶

double
two elements

✔

0.036 s

▶

simple
simple test

✔

0.036 s

▶

small_random
random, length = 100

✔

0.036 s

▶

small_random2
random, length = 1000

✔

0.040 s

expand all Performance tests

▶

medium_random
random, length = ~10,000

✔

0.044 s

▶

large_random
random, length = ~100,000

✔

0.136 s

▶

large_big_answer
0..01..1, length = ~100,000

✔

0.136 s

0.104 s

▶

large_alternate
0101..01, length = ~100,000

✔

0.128 s

▶

large_extreme
large test with all 1s/0s, length = ~100,000

✔

0.140 s

0.136 s

0.128 s