Test results - Codility

Tasks Details

easy

1. TapeEquilibrium

Minimize the value |(A[0] + ... + A[P-1]) - (A[P] + ... + A[N-1])|.

Task Score

100%

Correctness

100%

Performance

100%

A non-empty array A consisting of N integers is given. Array A represents numbers on a tape.

Any integer P, such that 0 < P < N, splits this tape into two non-empty parts: A[0], A[1], ..., A[P − 1] and A[P], A[P + 1], ..., A[N − 1].

The difference between the two parts is the value of: |(A[0] + A[1] + ... + A[P − 1]) − (A[P] + A[P + 1] + ... + A[N − 1])|

In other words, it is the absolute difference between the sum of the first part and the sum of the second part.

For example, consider array A such that:

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

We can split this tape in four places:

P = 1, difference = |3 − 10| = 7

P = 2, difference = |4 − 9| = 5

P = 3, difference = |6 − 7| = 1

P = 4, difference = |10 − 3| = 7

Write a function:

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

that, given a non-empty array A of N integers, returns the minimal difference that can be achieved.

For example, given:

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

the function should return 1, as explained above.

Write an efficient algorithm for the following assumptions:

N is an integer within the range [2..100,000];

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

Solution

Programming language used Java 8

Time spent on task 9 minutes

Notes

not defined yet

Code: 04:48:11 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: 04:48:17 UTC, java, autosave

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https://app.codility.com/demo/results/trainingY2KNXZ-9B6/

Code: 04:48:28 UTC, java, autosave

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import java.util.*;

class Solution {
    public int solution(int[] A) {
        int frontSum = 0;
        int rearSum = 0;
        int minSum = Integer.MAX_VALUE;
        
        for (int a : A) {
            rearSum += a;
        }
        
        for (int a : A) {
            frontSum += a;
            rearSum -= a;
            int diffSum = Math.abs(frontSum - rearSum);
            
            if (minSum > diffSum) {
                minSum = diffSum;
            }
        }
        
        return minSum;
    }
}

Code: 04:49:34 UTC, java, verify, result: Passed

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import java.util.*;

class Solution {
    public int solution(int[] A) {
        int frontSum = 0;
        int rearSum = 0;
        int minSum = Integer.MAX_VALUE;
        
        for (int a : A) {
            rearSum += a;
        }
        
        for (int a : A) {
            frontSum += a;
            rearSum -= a;
            int diffSum = Math.abs(frontSum - rearSum);
            
            if (minSum > diffSum) {
                minSum = diffSum;
            }
        }
        
        return minSum;
    }
}

User test case 1:

[0, 2]

Analysis

expand all Example tests

▶

example
example test

✔

0.004 s

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▶

test_data1

✔

0.004 s

OK
function result: 2

Code: 04:50:16 UTC, java, verify, result: Passed

show code in pop-up

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import java.util.*;

class Solution {
    public int solution(int[] A) {
        int frontSum = 0;
        int rearSum = 0;
        int minSum = Integer.MAX_VALUE;
        
        for (int a : A) {
            rearSum += a;
        }
        
        for (int a : A) {
            frontSum += a;
            rearSum -= a;
            int diffSum = Math.abs(frontSum - rearSum);
            
            if (minSum > diffSum) {
                minSum = diffSum;
            }
        }
        
        return minSum;
    }
}

User test case 1:

[0, 2]

Analysis

expand all Example tests

▶

example
example test

✔

0.004 s

expand all User tests

▶

test_data1

✔

0.004 s

OK
function result: 2

Code: 04:51:12 UTC, java, verify, result: Passed

show code in pop-up

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import java.util.*;

class Solution {
    public int solution(int[] A) {
        int frontSum = 0;
        int rearSum = 0;
        int minSum = Integer.MAX_VALUE;
        
        for (int a : A) {
            rearSum += a;
        }
        
        for (int a : A) {
            frontSum += a;
            rearSum -= a;
            int diffSum = Math.abs(frontSum - rearSum);
            
            if (minSum > diffSum) {
                minSum = diffSum;
            }
        }
        
        return minSum;
    }
}

User test case 1:

[0, 0]

Analysis

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▶

example
example test

✔

0.004 s

expand all User tests

▶

test_data1

✔

0.008 s

OK
function result: 0

Code: 04:51:27 UTC, java, verify, result: Passed

show code in pop-up

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import java.util.*;

class Solution {
    public int solution(int[] A) {
        int frontSum = 0;
        int rearSum = 0;
        int minSum = Integer.MAX_VALUE;
        
        for (int a : A) {
            rearSum += a;
        }
        
        for (int a : A) {
            frontSum += a;
            rearSum -= a;
            int diffSum = Math.abs(frontSum - rearSum);
            
            if (minSum > diffSum) {
                minSum = diffSum;
            }
        }
        
        return minSum;
    }
}

User test case 1:

[-1000, 1000]

Analysis

expand all Example tests

▶

example
example test

✔

0.004 s

expand all User tests

▶

test_data1

✔

0.004 s

OK
function result: 0

Code: 04:51:44 UTC, java, verify, result: Passed

show code in pop-up

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import java.util.*;

class Solution {
    public int solution(int[] A) {
        int frontSum = 0;
        int rearSum = 0;
        int minSum = Integer.MAX_VALUE;
        
        for (int a : A) {
            rearSum += a;
        }
        
        for (int a : A) {
            frontSum += a;
            rearSum -= a;
            int diffSum = Math.abs(frontSum - rearSum);
            
            if (minSum > diffSum) {
                minSum = diffSum;
            }
        }
        
        return minSum;
    }
}

User test case 1:

[1, 2]

Analysis

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▶

example
example test

✔

0.004 s

expand all User tests

▶

test_data1

✔

0.004 s

OK
function result: 1

Code: 04:52:05 UTC, java, verify, result: Passed

show code in pop-up

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import java.util.*;

class Solution {
    public int solution(int[] A) {
        int frontSum = 0;
        int rearSum = 0;
        int minSum = Integer.MAX_VALUE;
        
        for (int a : A) {
            rearSum += a;
        }
        
        for (int a : A) {
            frontSum += a;
            rearSum -= a;
            int diffSum = Math.abs(frontSum - rearSum);
            
            if (minSum > diffSum) {
                minSum = diffSum;
            }
        }
        
        return minSum;
    }
}

User test case 1:

[-1000, 1000]

Analysis

expand all Example tests

▶

example
example test

✔

0.004 s

expand all User tests

▶

test_data1

✔

0.004 s

OK
function result: 0

Code: 04:54:02 UTC, java, autosave

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import java.util.*;

class Solution {
    public int solution(int[] A) {
        int frontSum = 0;
        int rearSum = 0;
        int minSum = Integer.MAX_VALUE;
        
        for (int a : A) {
            rearSum += a;
        }
        
        for (int a : A) {
            frontSum += a;
            rearSum -= a;
            Sys
            int diffSum = Math.abs(frontSum - rearSum);
            
            if (minSum > diffSum) {
                minSum = diffSum;
            }
        }
        
        return minSum;
    }
}

Code: 04:54:11 UTC, java, verify, result: Failed

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import java.util.*;

class Solution {
    public int solution(int[] A) {
        int frontSum = 0;
        int rearSum = 0;
        int minSum = Integer.MAX_VALUE;
        
        for (int a : A) {
            rearSum += a;
        }
        
        for (int a : A) {
            frontSum += a;
            rearSum -= a;
            System.out.printon(fronSum + " " rearSum);
            int diffSum = Math.abs(frontSum - rearSum);
            
            if (minSum > diffSum) {
                minSum = diffSum;
            }
        }
        
        return minSum;
    }
}

Analysis

Compile error

Solution.java:16: error: ')' expected
            System.out.printon(fronSum + " " rearSum);
                                            ^
Solution.java:16: error: illegal start of expression
            System.out.printon(fronSum + " " rearSum);
                                                    ^
2 errors

Code: 04:54:16 UTC, java, verify, result: Failed

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import java.util.*;

class Solution {
    public int solution(int[] A) {
        int frontSum = 0;
        int rearSum = 0;
        int minSum = Integer.MAX_VALUE;
        
        for (int a : A) {
            rearSum += a;
        }
        
        for (int a : A) {
            frontSum += a;
            rearSum -= a;
            System.out.printon(fronSum + " " + rearSum);
            int diffSum = Math.abs(frontSum - rearSum);
            
            if (minSum > diffSum) {
                minSum = diffSum;
            }
        }
        
        return minSum;
    }
}

Analysis

Compile error

Solution.java:16: error: cannot find symbol
            System.out.printon(fronSum + " " + rearSum);
                               ^
  symbol:   variable fronSum
  location: class Solution
1 error

Code: 04:54:21 UTC, java, verify, result: Failed

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import java.util.*;

class Solution {
    public int solution(int[] A) {
        int frontSum = 0;
        int rearSum = 0;
        int minSum = Integer.MAX_VALUE;
        
        for (int a : A) {
            rearSum += a;
        }
        
        for (int a : A) {
            frontSum += a;
            rearSum -= a;
            System.out.printon(frontSum + " " + rearSum);
            int diffSum = Math.abs(frontSum - rearSum);
            
            if (minSum > diffSum) {
                minSum = diffSum;
            }
        }
        
        return minSum;
    }
}

Analysis

Compile error

Solution.java:16: error: cannot find symbol
            System.out.printon(frontSum + " " + rearSum);
                      ^
  symbol:   method printon(String)
  location: variable out of type PrintStream
1 error

Code: 04:54:25 UTC, java, verify, result: Passed

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import java.util.*;

class Solution {
    public int solution(int[] A) {
        int frontSum = 0;
        int rearSum = 0;
        int minSum = Integer.MAX_VALUE;
        
        for (int a : A) {
            rearSum += a;
        }
        
        for (int a : A) {
            frontSum += a;
            rearSum -= a;
            System.out.println(frontSum + " " + rearSum);
            int diffSum = Math.abs(frontSum - rearSum);
            
            if (minSum > diffSum) {
                minSum = diffSum;
            }
        }
        
        return minSum;
    }
}

User test case 1:

[-1000, 1000]

Analysis

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▶

example
example test

✔

0.004 s

stdout:

expand all User tests

▶

test_data1

✔

0.004 s

OK
function result: 0

stdout:

-1000 1000
0 0

Code: 04:55:40 UTC, java, autosave

show code in pop-up

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import java.util.*;

class Solution {
    public int solution(int[] A) {
        int frontSum = 0;
        int rearSum = 0;
        int minSum = Integer.MAX_VALUE;
        
        for (int a : A) {
            rearSum += a;
        }
        
        for (int i a : A) {
            frontSum += a;
            rearSum -= a;
            System.out.println(frontSum + " " + rearSum);
            int diffSum = Math.abs(frontSum - rearSum);
            
            if (minSum > diffSum) {
                minSum = diffSum;
            }
        }
        
        return minSum;
    }
}

Code: 04:56:02 UTC, java, autosave

show code in pop-up

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import java.util.*;

class Solution {
    public int solution(int[] A) {
        int frontSum = 0;
        int rearSum = 0;
        int minSum = Integer.MAX_VALUE;
        
        for (int a : A) {
            rearSum += a;
        }
        
        for (int i=0; i<A.length - 1; i++) {
            frontSum += a;
            rearSum -= a;
            System.out.println(frontSum + " " + rearSum);
            int diffSum = Math.abs(frontSum - rearSum);
            
            if (minSum > diffSum) {
                minSum = diffSum;
            }
        }
        
        return minSum;
    }
}

Code: 04:56:24 UTC, java, verify, result: Passed

show code in pop-up

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import java.util.*;

class Solution {
    public int solution(int[] A) {
        int frontSum = 0;
        int rearSum = 0;
        int minSum = Integer.MAX_VALUE;
        
        for (int a : A) {
            rearSum += a;
        }
        
        for (int i=0; i<A.length - 1; i++) {
            frontSum += A[i];
            rearSum -= A[i];
            int diffSum = Math.abs(frontSum - rearSum);
            
            if (minSum > diffSum) {
                minSum = diffSum;
            }
        }
        
        return minSum;
    }
}

User test case 1:

[-1000, 1000]

Analysis

expand all Example tests

▶

example
example test

✔

0.004 s

expand all User tests

▶

test_data1

✔

0.004 s

OK
function result: 2000

Code: 04:56:30 UTC, java, 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

import java.util.*;

class Solution {
    public int solution(int[] A) {
        int frontSum = 0;
        int rearSum = 0;
        int minSum = Integer.MAX_VALUE;
        
        for (int a : A) {
            rearSum += a;
        }
        
        for (int i=0; i<A.length - 1; i++) {
            frontSum += A[i];
            rearSum -= A[i];
            int diffSum = Math.abs(frontSum - rearSum);
            
            if (minSum > diffSum) {
                minSum = diffSum;
            }
        }
        
        return minSum;
    }
}

User test case 1:

[-1000, 1000]

Analysis

expand all Example tests

▶

example
example test

✔

0.004 s

expand all User tests

▶

test_data1

✔

0.004 s

OK
function result: 2000

Code: 04:56:34 UTC, java, 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

import java.util.*;

class Solution {
    public int solution(int[] A) {
        int frontSum = 0;
        int rearSum = 0;
        int minSum = Integer.MAX_VALUE;
        
        for (int a : A) {
            rearSum += a;
        }
        
        for (int i=0; i<A.length - 1; i++) {
            frontSum += A[i];
            rearSum -= A[i];
            int diffSum = Math.abs(frontSum - rearSum);
            
            if (minSum > diffSum) {
                minSum = diffSum;
            }
        }
        
        return minSum;
    }
}

Analysis summary

The solution obtained perfect score.

Analysis

Detected time complexity:

O(N)

expand all Example tests

▶

example
example test

✔

0.004 s

expand all Correctness tests

▶

double
two elements

✔

0.008 s

0.004 s

▶

simple_positive
simple test with positive numbers, length = 5

✔

0.004 s

▶

simple_negative
simple test with negative numbers, length = 5

✔

0.004 s

▶

small_random
random small, length = 100

✔

0.004 s

▶

small_range
range sequence, length = ~1,000

✔

0.004 s

▶

small
small elements

✔

0.004 s

expand all Performance tests

▶

medium_random1
random medium, numbers from 0 to 100, length = ~10,000

✔

0.020 s

▶

medium_random2
random medium, numbers from -1,000 to 50, length = ~10,000

✔

0.024 s

▶

large_ones
large sequence, numbers from -1 to 1, length = ~100,000

✔

0.160 s

▶

large_random
random large, length = ~100,000

✔

0.208 s

▶

large_sequence
large sequence, length = ~100,000

✔

0.092 s

▶

large_extreme
large test with maximal and minimal values, length = ~100,000

✔

0.228 s

0.252 s

0.184 s