Test results - Codility

Tasks Details

medium

1. MaxCounters

Calculate the values of counters after applying all alternating operations: increase counter by 1; set value of all counters to current maximum.

Task Score

100%

Correctness

Not assessed

Performance

Not assessed

You are given N counters, initially set to 0, and you have two possible operations on them:

increase(X) − counter X is increased by 1,

max counter − all counters are set to the maximum value of any counter.

A non-empty array A of M integers is given. This array represents consecutive operations:

if A[K] = X, such that 1 ≤ X ≤ N, then operation K is increase(X),

if A[K] = N + 1 then operation K is max counter.

For example, given integer N = 5 and array A such that:

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

the values of the counters after each consecutive operation will be:

(0, 0, 1, 0, 0) (0, 0, 1, 1, 0) (0, 0, 1, 2, 0) (2, 2, 2, 2, 2) (3, 2, 2, 2, 2) (3, 2, 2, 3, 2) (3, 2, 2, 4, 2)

The goal is to calculate the value of every counter after all operations.

Write a function:

class Solution { public int[] solution(int N, int[] A); }

that, given an integer N and a non-empty array A consisting of M integers, returns a sequence of integers representing the values of the counters.

Result array should be returned as an array of integers.

For example, given:

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

the function should return [3, 2, 2, 4, 2], as explained above.

Write an efficient algorithm for the following assumptions:

N and M are integers within the range [1..100,000];

each element of array A is an integer within the range [1..N + 1].

Solution

Programming language used Java 8

Time spent on task 50 minutes

Notes

not defined yet

Task timeline

Code: 00:48:04 UTC, java, verify, result: Passed

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class Solution {
    public int[] solution(int N, int[] A) {
        int MAX = 0, CI;
        int[] C = new int[N];
        
        for(int i = 0; i < A.length; i++)
        {
            CI = A[i]-1;
            if(A[i] <= N && A[i] >= 1)
            {
                C[CI] += 1;
                MAX = Math.max(MAX,C[CI]);
            }else if(A[i] == N + 1){
                for(int j = 0; j < C.length; j++)
                    C[j] = MAX;
            }
        }
        return C;
    }
}

Analysis

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example
example test

✔

0.300 s

Code: 01:09:09 UTC, java, verify, result: Failed

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class Solution {
    public int[] solution(int N, int[] A) {
        int MAX = 0, B = 0, CI;
        int[] C = new int[N];
        
        for(int i = 0; i < A.length; i++)
        {
            CI = A[i]-1;
            if(A[i] <= N && A[i] >= 1)
            {
                C[CI] += 1;
                MAX = Math.max(MAX,C[CI]);
            }else if(A[i] == N + 1){
                B = MAX;
            }
        }
        
        for(int i = 0; i < C.length; i++)
            C[i] = Math.max(C[i],B);
        
        return C;
    }
}

Analysis

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▶

example
example test

✘

WRONG ANSWER
got [2, 2, 2, 4, 2] expected [3, 2, 2, 4, 2]

0.300 s

WRONG ANSWER, got [2, 2, 2, 4, 2] expected [3, 2, 2, 4, 2]

Code: 01:10:57 UTC, java, verify, result: Failed

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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 22 23 24

class Solution {
    public int[] solution(int N, int[] A) {
        int MAX = 0, B = 0, CI;
        int[] C = new int[N];
        
        for(int i = 0; i < A.length; i++)
        {
            CI = A[i]-1;
            if(A[i] <= N && A[i] >= 1)
            {
                C[CI] += 1;
                MAX = Math.max(MAX,C[CI]);
            }else if(A[i] == N + 1){
                C[CI] = MAX;
                B = MAX;
            }
        }
        
        for(int i = 0; i < C.length; i++)
            C[i] = Math.max(C[i],B);
        
        return C;
    }
}

Analysis

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example
example test

✘

RUNTIME ERROR
tested program terminated unexpectedly

0.300 s

RUNTIME ERROR, tested program terminated unexpectedly

stdout:

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 5
	at Solution.solution(Solution.java:14)
	at wrapper.run(wrapper.java:28)
	at wrapper.main(wrapper.java:21)

Code: 01:13:32 UTC, java, verify, result: Failed

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class Solution {
    public int[] solution(int N, int[] A) {
        int MAX = 0, B = 0, CI;
        int[] C = new int[N];
        
        for(int i = 0; i < A.length; i++)
        {
            CI = A[i]-1;
            if(A[i] <= N && A[i] >= 1)
            {
                C[CI] += 1;
                MAX = Math.max(MAX,C[CI]);
            }else if(A[i] == N + 1)
            {
                B = MAX;
            }
        }
        
        for(int i = 0; i < C.length; i++)
            C[i] = Math.max(C[i],B);
        
        return C;
    }
}

Analysis

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▶

example
example test

✘

WRONG ANSWER
got [2, 2, 2, 4, 2] expected [3, 2, 2, 4, 2]

0.300 s

WRONG ANSWER, got [2, 2, 2, 4, 2] expected [3, 2, 2, 4, 2]

Code: 01:14:19 UTC, java, verify, result: Failed

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class Solution {
    public int[] solution(int N, int[] A) {
        int MAX = 0, B = 0, CI;
        int[] C = new int[N];
        
        for(int i = 0; i < A.length; i++)
        {
            CI = A[i]-1;
            if(A[i] <= N && A[i] >= 1)
            {
                C[CI] += 1;
                MAX = Math.max(MAX,C[CI]);
            }else if(A[i] == N + 1)
            {
                B = MAX;
            }
        }
        
        for(int i = 0; i < C.length; i++)
            //C[i] = Math.max(C[i],B);
        
        return C;
    }
}

Analysis

Compile error

Solution.java:23: missing return statement
    }
    ^
1 error

Code: 01:14:29 UTC, java, verify, result: Failed

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class Solution {
    public int[] solution(int N, int[] A) {
        int MAX = 0, B = 0, CI;
        int[] C = new int[N];
        
        for(int i = 0; i < A.length; i++)
        {
            CI = A[i]-1;
            if(A[i] <= N && A[i] >= 1)
            {
                C[CI] += 1;
                MAX = Math.max(MAX,C[CI]);
            }else if(A[i] == N + 1)
            {
                B = MAX;
            }
        }
        
        for(int i = 0; i < C.length; i++);
            //C[i] = Math.max(C[i],B);
        
        return C;
    }
}

Analysis

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▶

example
example test

✘

WRONG ANSWER
got [1, 0, 1, 4, 0] expected [3, 2, 2, 4, 2]

0.310 s

WRONG ANSWER, got [1, 0, 1, 4, 0] expected [3, 2, 2, 4, 2]

Code: 01:17:57 UTC, java, verify, result: Failed

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class Solution {
    public int[] solution(int N, int[] A) {
        int MAX = 0, B = 0, CI;
        int[] C = new int[N];
        
        for(int i = 0; i < A.length; i++)
        {
            CI = A[i]-1;
            if(A[i] <= N && A[i] >= 1)
            {
                C[CI] += 1;
                MAX = Math.max(MAX,C[CI]);
            }else if(A[i] == N + 1)
            {
                B = MAX;
            }
        }
        
        for(int i = 0; i < C.length; i++)
            C[i] = Math.max(C[i],B);
        
        return C;
    }
}

Analysis

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▶

example
example test

✘

WRONG ANSWER
got [2, 2, 2, 4, 2] expected [3, 2, 2, 4, 2]

0.290 s

WRONG ANSWER, got [2, 2, 2, 4, 2] expected [3, 2, 2, 4, 2]

Code: 01:24:41 UTC, java, verify, result: Failed

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class Solution {
    public int[] solution(int N, int[] A) {
        int MAX = 0, B = 0, CI;
        int[] C = new int[N];
        
        for(int i = 0; i < A.length; i++)
        {
            CI = A[i]-1;
            if(A[i] <= N && A[i] >= 1)
            {
                C[CI] = B + 1;
                MAX = Math.max(MAX,C[CI]);
            }else if(A[i] == N + 1)
            {
                B = MAX;
            }
        }
        
        for(int i = 0; i < C.length; i++)
            C[i] = Math.max(C[i],B);
        
        return C;
    }
}

Analysis

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▶

example
example test

✘

WRONG ANSWER
got [2, 1, 1, 2, 1] expected [3, 2, 2, 4, 2]

0.300 s

WRONG ANSWER, got [2, 1, 1, 2, 1] expected [3, 2, 2, 4, 2]

Code: 01:25:06 UTC, java, verify, result: Failed

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class Solution {
    public int[] solution(int N, int[] A) {
        int MAX = 0, B = 0, CI;
        int[] C = new int[N];
        
        for(int i = 0; i < A.length; i++)
        {
            CI = A[i]-1;
            if(A[i] <= N && A[i] >= 1)
            {
                C[CI] = B + 1;
                MAX = Math.max(MAX,C[CI]);
            }else if(A[i] == N + 1)
            {
                B = MAX;
            }
        }
        
        for(int i = 0; i < C.length; i++)
            C[i] = Math.max(C[i],MAX);
        
        return C;
    }
}

Analysis

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▶

example
example test

✘

WRONG ANSWER
got [2, 2, 2, 2, 2] expected [3, 2, 2, 4, 2]

0.300 s

WRONG ANSWER, got [2, 2, 2, 2, 2] expected [3, 2, 2, 4, 2]

Code: 01:25:17 UTC, java, verify, result: Failed

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class Solution {
    public int[] solution(int N, int[] A) {
        int MAX = 0, B = 0, CI;
        int[] C = new int[N];
        
        for(int i = 0; i < A.length; i++)
        {
            CI = A[i]-1;
            if(A[i] <= N && A[i] >= 1)
            {
                C[CI] = B + 1;
                MAX = Math.max(MAX,C[CI]);
            }else if(A[i] == N + 1)
            {
                B = MAX;
            }
        }
        
        for(int i = 0; i < C.length; i++)
            C[i] = Math.max(C[i],B);
        
        return C;
    }
}

Analysis

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▶

example
example test

✘

WRONG ANSWER
got [2, 1, 1, 2, 1] expected [3, 2, 2, 4, 2]

0.300 s

WRONG ANSWER, got [2, 1, 1, 2, 1] expected [3, 2, 2, 4, 2]

Code: 01:27:34 UTC, java, verify, result: Failed

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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 22 23 24

class Solution {
    public int[] solution(int N, int[] A) {
        int MAX = 0, B = 0, CI;
        int[] C = new int[N];
        
        for(int i = 0; i < A.length; i++)
        {
            CI = A[i]-1;
            if(A[i] <= N && A[i] >= 1)
            {
                C[CI] += B + 1;
                MAX = Math.max(MAX,C[CI]);
            }else if(A[i] == N + 1)
            {
                B = MAX;
            }
        }
        
        for(int i = 0; i < C.length; i++)
            C[i] = Math.max(C[i],B);
        
        return C;
    }
}

Analysis

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▶

example
example test

✘

WRONG ANSWER
got [3, 2, 2, 8, 2] expected [3, 2, 2, 4, 2]

0.310 s

WRONG ANSWER, got [3, 2, 2, 8, 2] expected [3, 2, 2, 4, 2]

Code: 01:30:06 UTC, java, verify, result: Passed

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class Solution {
    public int[] solution(int N, int[] A) {
        int MAX = 0, B = 0, CI;
        int[] C = new int[N];
        
        for(int i = 0; i < A.length; i++)
        {
            CI = A[i]-1;
            if(A[i] <= N && A[i] >= 1)
            {
                C[CI] = Math.max(B,C[CI]) + 1;
                MAX = Math.max(MAX,C[CI]);
            }else if(A[i] == N + 1)
            {
                B = MAX;
            }
        }
        
        for(int i = 0; i < C.length; i++)
            C[i] = Math.max(C[i],B);
        
        return C;
    }
}

Analysis

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example
example test

✔

0.300 s

Code: 01:30:17 UTC, java, verify, result: Passed

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class Solution {
    public int[] solution(int N, int[] A) {
        int MAX = 0, B = 0, CI;
        int[] C = new int[N];
        
        for(int i = 0; i < A.length; i++)
        {
            CI = A[i]-1;
            if(A[i] <= N && A[i] >= 1)
            {
                C[CI] = Math.max(B,C[CI]) + 1;
                MAX = Math.max(MAX,C[CI]);
            }else if(A[i] == N + 1)
            {
                B = MAX;
            }
        }
        
        for(int i = 0; i < C.length; i++)
            C[i] = Math.max(C[i],B);
        
        return C;
    }
}

Analysis

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example
example test

✔

0.310 s

Code: 01:30:22 UTC, java, final, score: 100

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class Solution {
    public int[] solution(int N, int[] A) {
        int MAX = 0, B = 0, CI;
        int[] C = new int[N];
        
        for(int i = 0; i < A.length; i++)
        {
            CI = A[i]-1;
            if(A[i] <= N && A[i] >= 1)
            {
                C[CI] = Math.max(B,C[CI]) + 1;
                MAX = Math.max(MAX,C[CI]);
            }else if(A[i] == N + 1)
            {
                B = MAX;
            }
        }
        
        for(int i = 0; i < C.length; i++)
            C[i] = Math.max(C[i],B);
        
        return C;
    }
}

Analysis summary

The solution obtained perfect score.

Analysis

Detected time complexity:

O(N + M)

expand all Example tests

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example
example test

✔

0.310 s

expand all Assessment tests

▶

extreme_small
all max_counter operations

✔

0.310 s

▶

single
only one counter

✔

0.300 s

▶

small_random1
small random test, 6 max_counter operations

✔

0.310 s

▶

small_random2
small random test, 10 max_counter operations

✔

0.320 s

▶

medium_random1
medium random test, 50 max_counter operations

✔

0.330 s

▶

medium_random2
medium random test, 500 max_counter operations

✔

0.330 s

▶

large_random1
large random test, 2120 max_counter operations

✔

0.390 s

▶

large_random2
large random test, 10000 max_counter operations

✔

0.400 s

▶

extreme_large
all max_counter operations

✔

0.440 s