Test results - Codility

Tasks Details

easy

1. StoneWall

Cover "Manhattan skyline" using the minimum number of rectangles.

Task Score

100%

Correctness

100%

Performance

100%

You are going to build a stone wall. The wall should be straight and N meters long, and its thickness should be constant; however, it should have different heights in different places. The height of the wall is specified by an array H of N positive integers. H[I] is the height of the wall from I to I+1 meters to the right of its left end. In particular, H[0] is the height of the wall's left end and H[N−1] is the height of the wall's right end.

The wall should be built of cuboid stone blocks (that is, all sides of such blocks are rectangular). Your task is to compute the minimum number of blocks needed to build the wall.

Write a function:

def solution(H)

that, given an array H of N positive integers specifying the height of the wall, returns the minimum number of blocks needed to build it.

For example, given array H containing N = 9 integers:

H[0] = 8 H[1] = 8 H[2] = 5 H[3] = 7 H[4] = 9 H[5] = 8 H[6] = 7 H[7] = 4 H[8] = 8

the function should return 7. The figure shows one possible arrangement of seven blocks.

Write an efficient algorithm for the following assumptions:

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

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

Solution

Programming language used Python

Time spent on task 83 minutes

Notes

not defined yet

Task timeline

Code: 06:19:14 UTC, java, autosave

show code in pop-up

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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[] H) {
        // write your code in Java SE 8
    }
}

Code: 06:19:43 UTC, py, autosave

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1 2 3 4 5 6

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

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

Code: 07:22:58 UTC, py, autosave

show code in pop-up

1 2 3 4

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

def solution(H):

Code: 07:23:12 UTC, py, verify, result: Failed

show code in pop-up

1 2 3 4 5 6 7

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

def solution(H):

    for hei in H:
        print(hei)

Analysis

expand all Example tests

▶

example

✘

RUNTIME ERROR
tested program terminated with exit code 1

0.036 s

RUNTIME ERROR, tested program terminated with exit code 1

stderr:

Invalid result type, int expected, <class 'NoneType'> found.

stdout:

Code: 07:23:28 UTC, py, autosave

show code in pop-up

1 2 3 4 5 6 7 8 9 10

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

def solution(H):

    stack = []
    
    for hei in H:

Code: 07:24:35 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(H):

    stack = []

    for hei in H:
        for

Code: 07:24:59 UTC, py, autosave

show code in pop-up

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

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

def solution(H):

    stack = []

    for hei in H:
        if stack:
            if 
        else:
            stack.append(hei)

Code: 07:25:10 UTC, py, autosave

show code in pop-up

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

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

def solution(H):

    stack = []

    for hei in H:
        if stack:
            if stack[-1]
        else:
            stack.append(hei)

Code: 07:25:21 UTC, py, autosave

show code in pop-up

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

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

def solution(H):

    stack = []

    for hei in H:
        if stack:
            while stack[-1] > stack[]
        else:
            stack.append(hei)

Code: 07:25:32 UTC, py, autosave

show code in pop-up

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

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

def solution(H):

    stack = []

    for hei in H:
        if stack:
            while stack[-1] < stack[]
        else:
            stack.append(hei)

Code: 07:25:48 UTC, py, autosave

show code in pop-up

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

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

def solution(H):

    stack = []

    for hei in H:
        if stack:
            while stack[-1] > hei:
                stack.pop()
        else:
            stack.append(hei)

Code: 07:26:07 UTC, py, autosave

show code in pop-up

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

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

def solution(H):

    stack = []

    for hei in H:
        if stack:
            while stack[-1] > hei:
                stack.pop()
            
        else:
            stack.append(hei)

Code: 07:26:41 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(H):

    stack = []

    for hei in H:
        if stack:
            while stack[-1] > hei:
                stack.pop()

Code: 07:26:52 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(H):

    stack = []

    for hei in H:
        if stack:
            while stack[-1] > hei:
                stack.pop()

Code: 07:27:03 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(H):

    stack = []

    for hei in H:
        if stack:
            while stack[-1] > hei:
                stack.pop()

Code: 07:28:02 UTC, py, autosave

show code in pop-up

1 2 3 4 5 6 7 8 9 10 11 12 13

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

def solution(H):

    stack = []

    for hei in H:
        if stack:
            while stack[-1] > hei:
                stack.pop()

Code: 07:28:13 UTC, py, autosave

show code in pop-up

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

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

def solution(H):

    stack = []

    for hei in H:
        if stack:
            while stack[-1] > hei:
                stack.pop()
        else:
            stack.append(hei)

Code: 07:28:49 UTC, py, autosave

show code in pop-up

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

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

def solution(H):

    stack = []

    for hei in H:
        if stack:
            while stack[-1] > hei:
                stack.pop()
            
        else:
            stack.append(hei)

Code: 07:29:13 UTC, py, verify, result: Failed

show code in pop-up

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

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

def solution(H):

    stack = []

    for hei in H:
        if stack:
            while stack[-1] > hei:
                stack.pop()
                
        if not stack:
            stack.append(hei)

Analysis

expand all Example tests

▶

example

✘

RUNTIME ERROR
tested program terminated with exit code 1

0.040 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( H )
  File "/tmp/solution.py", line 10, in solution
    while stack[-1] > hei:
IndexError: list index out of range

Code: 07:31:21 UTC, py, autosave

show code in pop-up

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

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

def solution(H):

    stack = []

    for hei in H:
        if stack:
            prin
            while stack[-1] > hei:
                stack.pop()

        if not stack:
            stack.append(hei)

Code: 07:31:33 UTC, py, autosave

show code in pop-up

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

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

def solution(H):

    stack = []

    for hei in H:
        if stack:
            print(stack[-1])
            while stack[-1] > hei:
                stack.pop()

        if not stack:
            stack.append(hei)

Code: 07:31:34 UTC, py, verify, result: Failed

show code in pop-up

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

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

def solution(H):

    stack = []

    for hei in H:
        if stack:
            print(stack[-1])
            while stack[-1] > hei:
                stack.pop()

        if not stack:
            stack.append(hei)

Analysis

expand all Example tests

▶

example

✘

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( H )
  File "/tmp/solution.py", line 11, in solution
    while stack[-1] > hei:
IndexError: list index out of range

stdout:

8
8

Code: 07:31:55 UTC, py, verify, result: Failed

show code in pop-up

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

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

def solution(H):

    stack = []

    for hei in H:
        if stack:
            print("stack ::: " + str(stack[-1]))
            while stack[-1] > hei:
                stack.pop()

        if not stack:
            stack.append(hei)

Analysis

expand all Example tests

▶

example

✘

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( H )
  File "/tmp/solution.py", line 11, in solution
    while stack[-1] > hei:
IndexError: list index out of range

stdout:

stack ::: 8
stack ::: 8

Code: 07:32:03 UTC, py, autosave

show code in pop-up

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.
# print("this is a debug message")

def solution(H):

    stack = []

    for hei in H:
        if stack:
            print("hei" ::: + star)
            print("stack ::: " + str(stack[-1]))
            while stack[-1] > hei:
                stack.pop()

        if not stack:
            stack.append(hei)

Code: 07:32:14 UTC, py, autosave

show code in pop-up

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.
# print("this is a debug message")

def solution(H):

    stack = []

    for hei in H:
        if stack:
            print("hei" ::: + str(hei))
            print("stack ::: " + str(stack[-1]))
            while stack[-1] > hei:
                stack.pop()

        if not stack:
            stack.append(hei)

Code: 07:32:33 UTC, py, verify, result: Failed

show code in pop-up

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.
# print("this is a debug message")

def solution(H):

    stack = []

    for hei in H:
        if stack:
            print(hei)
            print("stack ::: " + str(stack[-1]))
            while stack[-1] > hei:
                stack.pop()

        if not stack:
            stack.append(hei)

Analysis

expand all Example tests

▶

example

✘

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( H )
  File "/tmp/solution.py", line 12, in solution
    while stack[-1] > hei:
IndexError: list index out of range

stdout:

8
stack ::: 8
5
stack ::: 8

Code: 07:32:51 UTC, py, autosave

show code in pop-up

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.
# print("this is a debug message")

def solution(H):

    stack = []

    for hei in H:
        if stack:
            print(hei)
            print("stack ::: " + str(stack[-1]))
            while staclstack[-1] > hei:
                stack.pop()

        if not stack:
            stack.append(hei)

Code: 07:32:59 UTC, py, verify, result: Failed

show code in pop-up

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.
# print("this is a debug message")

def solution(H):

    stack = []

    for hei in H:
        if stack:
            print(hei)
            print("stack ::: " + str(stack[-1]))
            while stack and stack[-1] > hei:
                stack.pop()

        if not stack:
            stack.append(hei)

Analysis

expand all Example tests

▶

example

✘

RUNTIME ERROR
tested program terminated with exit code 1

0.040 s

RUNTIME ERROR, tested program terminated with exit code 1

stderr:

Invalid result type, int expected, <class 'NoneType'> found.

stdout:

8
stack ::: 8
5
stack ::: 8
7
stack ::: 5
9
stack ::: 5
8
stack ::: 5
7
stack ::: 5
4
stack ::: 5
8
stack ::: 4

Code: 07:33:22 UTC, py, autosave

show code in pop-up

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

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

def solution(H):

    stack = []

    for hei in H:

        while stack and stack[-1] > hei:
                stack.pop()

        if not stack:
            stack.append(hei)

Code: 07:33:26 UTC, py, verify, result: Failed

show code in pop-up

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

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

def solution(H):

    stack = []

    for hei in H:

        while stack and stack[-1] > hei:
            stack.pop()

        if not stack:
            stack.append(hei)

Analysis

expand all Example tests

▶

example

✘

RUNTIME ERROR
tested program terminated with exit code 1

0.036 s

RUNTIME ERROR, tested program terminated with exit code 1

stderr:

Invalid result type, int expected, <class 'NoneType'> found.

Code: 07:33:34 UTC, py, autosave

show code in pop-up

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

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

def solution(H):

    stack = []

    for hei in H:
        while stack and stack[-1] > hei:
            stack.pop()

        if not stack:
            stack.append(hei)

Code: 07:34:02 UTC, py, autosave

show code in pop-up

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

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

def solution(H):

    stack = []
    count = 0

    for hei in H:
        while stack and stack[-1] > hei:
            stack.pop()

        if not stack:
            stack.append(hei)

Code: 07:34:14 UTC, py, autosave

show code in pop-up

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

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

def solution(H):

    stack = []
    count = 0

    for hei in H:
        while stack and stack[-1] > hei:
            stack.pop()


        stack.append(hei)

Code: 07:37:10 UTC, py, autosave

show code in pop-up

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

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

def solution(H):

    stack = []
    count = 0

    for hei in H:
        while stack and stack[-1] > hei:
            stack.pop()

    
        stack.append(hei)

Code: 07:37:23 UTC, py, autosave

show code in pop-up

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

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

def solution(H):

    stack = []
    count = 0

    for hei in H:
        while stack and stack[-1] > hei:
            stack.pop()

        if not stack:
          stack.append(hei)

Code: 07:37:34 UTC, py, autosave

show code in pop-up

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

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

def solution(H):

    stack = []
    count = 0

    for hei in H:
        while stack and stack[-1] > hei:
            stack.pop()

        if not stack:
            stack.append()

Code: 07:37:45 UTC, py, autosave

show code in pop-up

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

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

def solution(H):

    stack = []
    count = 0

    for hei in H:
        while stack and stack[-1] > hei:
            stack.pop()

        if not stack:
            stack.append(hei)

Code: 07:38:19 UTC, py, autosave

show code in pop-up

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

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

def solution(H):

    stack = []
    count = 0

    for hei in H:
        while stack and stack[-1] > hei:
            stack.pop()

        if not stack p:
            stack.append(hei)

Code: 07:38:30 UTC, py, autosave

show code in pop-up

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

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

def solution(H):

    stack = []
    count = 0

    for hei in H:
        while stack and stack[-1] > hei:
            stack.pop()

        if not stack or :
            stack.append(hei)

Code: 07:40:36 UTC, py, autosave

show code in pop-up

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

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

def solution(H):

    stack = []
    count = 0

    for hei in H:
        while stack and stack[-1] > hei:
            stack.pop()

        if not stack or stac:
            stack.append(hei)

Code: 07:40:47 UTC, py, autosave

show code in pop-up

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

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

def solution(H):

    stack = []
    count = 0

    for hei in H:
        while stack and stack[-1] > hei:
            stack.pop()

        if not stack or stack[-1] < hei:
            stack.append(hei)

Code: 07:40:53 UTC, py, verify, result: Failed

show code in pop-up

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

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

def solution(H):

    stack = []
    count = 0

    for hei in H:
        while stack and stack[-1] > hei:
            stack.pop()

        if not stack or stack[-1] < hei:
            stack.append(hei)

Analysis

expand all Example tests

▶

example

✘

RUNTIME ERROR
tested program terminated with exit code 1

0.044 s

RUNTIME ERROR, tested program terminated with exit code 1

stderr:

Invalid result type, int expected, <class 'NoneType'> found.

Code: 07:41:06 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

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

def solution(H):

    stack = []
    count = 0

    for hei in H:
        while stack and stack[-1] > hei:
            stack.pop()

        if not stack or stack[-1] < hei:
            stack.append(hei)        
            count += 1

    return count

Analysis

expand all Example tests

▶

example

✔

0.036 s

Code: 07:41:11 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

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

def solution(H):

    stack = []
    count = 0

    for hei in H:
        while stack and stack[-1] > hei:
            stack.pop()

        if not stack or stack[-1] < hei:
            stack.append(hei)        
            count += 1

    return count

Analysis

expand all Example tests

▶

example

✔

0.036 s

Code: 07:41:13 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(H):

    stack = []
    count = 0

    for hei in H:
        while stack and stack[-1] > hei:
            stack.pop()

        if not stack or stack[-1] < hei:
            stack.append(hei)        
            count += 1

    return count

Analysis summary

The solution obtained perfect score.

Analysis

Detected time complexity:

O(N)

expand all Example tests

▶

example

✔

0.036 s

expand all Correctness tests

▶

simple1

✔

0.036 s

▶

simple2

✔

0.036 s

▶

simple3

✔

0.036 s

▶

simple4

✔

0.036 s

▶

boundary_cases

✔

0.036 s

expand all Performance tests

▶

medium1

✔

0.036 s

▶

medium2

✔

0.036 s

▶

medium3

✔

0.036 s

▶

medium4

✔

0.036 s

▶

large_piramid

✔

0.168 s

▶

large_increasing_decreasing

✔

0.160 s

0.180 s

▶

large_up_to_20

✔

0.172 s

▶

large_up_to_100

✔

0.172 s

▶

large_max

✔

0.176 s