Test results - Codility

Tasks Details

easy

1. StrSymmetryPoint

Find a symmetry point of a string, if any.

Task Score

100%

Correctness

100%

Performance

100%

Write a function:

function solution(S);

that, given a string S, returns the index (counting from 0) of a character such that the part of the string to the left of that character is a reversal of the part of the string to its right. The function should return −1 if no such index exists.

Note: reversing an empty string (i.e. a string whose length is zero) gives an empty string.

For example, given a string:

"racecar"

the function should return 3, because the substring to the left of the character "e" at index 3 is "rac", and the one to the right is "car".

Given a string:

"x"

the function should return 0, because both substrings are empty.

Write an efficient algorithm for the following assumptions:

the length of string S is within the range [0..2,000,000].

Solution

Programming language used JavaScript

Time spent on task 24 minutes

Notes

not defined yet

Code: 12:36:08 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(String S) {
        // write your code in Java SE 8
    }
}

Code: 12:36:12 UTC, js, autosave

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

function solution(S) {
    // write your code in JavaScript (Node.js 8.9.4)
}

Code: 12:36:19 UTC, js, autosave

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1 2 3 4 5 6 7

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

function solution(S) {
    // write your code in JavaScript (Node.js 8.9.4)
    
}

Code: 12:36:29 UTC, js, autosave

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

function solution(S) {
    // write your code in JavaScript (Node.js 8.9.4)
    let i = 
}

Code: 12:37:22 UTC, js, autosave

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

function solution(S) {
    // write your code in JavaScript (Node.js 8.9.4)
    let i = 0
}

Code: 12:37:33 UTC, js, autosave

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

function solution(S) {
    // write your code in JavaScript (Node.js 8.9.4)
    let start = 0;
    let j
}

Code: 12:37:47 UTC, js, autosave

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1 2 3 4 5 6 7

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

function solution(S) {
    // write your code in JavaScript (Node.js 8.9.4)
    
}

Code: 12:38:17 UTC, js, autosave

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1 2 3 4 5 6 7 8 9

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

function solution(S) {
    // write your code in JavaScript (Node.js 8.9.4)
    let start = 0;
    let end = S.length - 1;
    while start
}

Code: 12:38:30 UTC, js, autosave

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

function solution(S) {
    // write your code in JavaScript (Node.js 8.9.4)
    let start = 0;
    let end = S.length - 1;
    while (start < end) {
        
    }
}

Code: 12:40:33 UTC, js, autosave

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

function solution(S) {
    // write your code in JavaScript (Node.js 8.9.4)
    let start = 0;
    let end = S.length - 1;
    while (start < end) {
        
    }
}

Code: 12:40:52 UTC, js, autosave

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

function solution(S) {
    // write your code in JavaScript (Node.js 8.9.4)
    let start = 0;
    let end = S.length - 1;
    while (start < end) {
        
    }
}

function reverseString(S) {
    
}

Code: 12:41:22 UTC, js, autosave

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

function solution(S) {
    // write your code in JavaScript (Node.js 8.9.4)
    let start = 0;
    let end = S.length - 1;
    while (start < end) {
        
    }
}

function reverseString(S) {
    let split = S.split('');
    let reverseSplit = split.reverse()
}

Code: 12:41:39 UTC, js, autosave

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

function solution(S) {
    // write your code in JavaScript (Node.js 8.9.4)
    let start = 0;
    let end = S.length - 1;
    while (start < end) {
        
    }
}

function reverseString(S) {
    let split = S.split('');
    let reverseSplit = split.reverse();
    return S.
}

Code: 12:41:50 UTC, js, autosave

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

function solution(S) {
    // write your code in JavaScript (Node.js 8.9.4)
    let start = 0;
    let end = S.length - 1;
    while (start < end) {
        
    }
}

function reverseString(S) {
    let split = S.split('');
    let reverseSplit = split.reverse();
    return S.join('')
}

Code: 12:42:10 UTC, js, autosave

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

function solution(S) {
    // write your code in JavaScript (Node.js 8.9.4)
    let start = 0;
    let end = S.length - 1;
    while (start < end) {
        
    }
}

function reverseString(S) {
    let split = S.split('').reverse();
    let reverseSplit = split.reverse();
    return S.join('')
}

Code: 12:42:26 UTC, js, autosave

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

function solution(S) {
    // write your code in JavaScript (Node.js 8.9.4)
    let start = 0;
    let end = S.length - 1;
    while (start < end) {
        
    }
}

function reverseString(S) {
    return S.split('').reverse().join('');

}

Code: 12:43:13 UTC, js, autosave

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

function solution(S) {
    // write your code in JavaScript (Node.js 8.9.4)
    if
}

function reverseString(S) {
    return S.split('').reverse().join('');

}

Code: 12:43:23 UTC, js, autosave

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

function solution(S) {
    // write your code in JavaScript (Node.js 8.9.4)
    if (S.length )
}

function reverseString(S) {
    return S.split('').reverse().join('');

}

Code: 12:51:25 UTC, js, autosave

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

function solution(S) {
    // write your code in JavaScript (Node.js 8.9.4)
    if (S.length / )
}

function reverseString(S) {
    return S.split('').reverse().join('');

}

Code: 12:51:35 UTC, js, autosave

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

function solution(S) {
    // write your code in JavaScript (Node.js 8.9.4)
    if (S.length % 2 === 0) {
        
    }
}

function reverseString(S) {
    return S.split('').reverse().join('');

}

Code: 12:51:54 UTC, js, autosave

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

function solution(S) {
    // write your code in JavaScript (Node.js 8.9.4)
    if (S.length % 2 === 0) {
        return 
    }
}

function reverseString(S) {
    return S.split('').reverse().join('');

}

Code: 12:52:09 UTC, js, autosave

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

function solution(S) {
    // write your code in JavaScript (Node.js 8.9.4)
    if (S.length % 2 === 0) {
        return -1;
    }
    
}

function reverseString(S) {
    return S.split('').reverse().join('');

}

Code: 12:55:24 UTC, js, autosave

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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.
// console.log('this is a debug message');

function solution(S) {
    // write your code in JavaScript (Node.js 8.9.4)
    if (S.length % 2 === 0) {
        return -1;
    }
    let 
}

function reverseString(S) {
    return S.split('').reverse().join('');

}

Code: 12:55:54 UTC, js, autosave

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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.
// console.log('this is a debug message');

function solution(S) {
    // write your code in JavaScript (Node.js 8.9.4)
    if (S.length % 2 === 0) {
        return -1;
    }
    let mid = Math.floor(S.length / 2);
    let startString = S
}

function reverseString(S) {
    return S.split('').reverse().join('');

}

Code: 12:56:04 UTC, js, autosave

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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.
// console.log('this is a debug message');

function solution(S) {
    // write your code in JavaScript (Node.js 8.9.4)
    if (S.length % 2 === 0) {
        return -1;
    }
    let mid = Math.floor(S.length / 2);
    let startString = S.slice(0, mid)
}

function reverseString(S) {
    return S.split('').reverse().join('');

}

Code: 12:57:02 UTC, js, autosave

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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.
// console.log('this is a debug message');

function solution(S) {
    // write your code in JavaScript (Node.js 8.9.4)
    if (S.length % 2 === 0) {
        return -1;
    }
    let mid = Math.floor(S.length / 2);
    let startString = S.slice(0, mid);
    
}

function reverseString(S) {
    return S.split('').reverse().join('');

}

Code: 12:57:32 UTC, js, autosave

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

function solution(S) {
    // write your code in JavaScript (Node.js 8.9.4)
    if (S.length % 2 === 0) {
        return -1;
    }
    let mid = Math.floor(S.length / 2);
    let startString = S.slice(0, mid);
    let endString = reverseString(S.slice(mid+1));
    if 
}

function reverseString(S) {
    return S.split('').reverse().join('');

}

Code: 12:57:55 UTC, js, autosave

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

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

function solution(S) {
    // write your code in JavaScript (Node.js 8.9.4)
    if (S.length % 2 === 0) {
        return -1;
    }
    let mid = Math.floor(S.length / 2);
    let startString = S.slice(0, mid);
    let endString = reverseString(S.slice(mid+1));
    if (startString === S)
}

function reverseString(S) {
    return S.split('').reverse().join('');

}

Code: 12:58:09 UTC, js, autosave

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

function solution(S) {
    // write your code in JavaScript (Node.js 8.9.4)
    if (S.length % 2 === 0) {
        return -1;
    }
    if (S.length)
    let mid = Math.floor(S.length / 2);
    let startString = S.slice(0, mid);
    let endString = reverseString(S.slice(mid+1));
    if (startString === S)
}

function reverseString(S) {
    return S.split('').reverse().join('');

}

Code: 12:58:30 UTC, js, autosave

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

function solution(S) {
    // write your code in JavaScript (Node.js 8.9.4)
    if (S.length % 2 === 0) {
        return -1;
    }
    if (S.length === 1) {
        return 0;
    }
    let mid = Math.floor(S.length / 2);
    let startString = S.slice(0, mid);
    let endString = reverseString(S.slice(mid+1));
    if (startString === S)
}

function reverseString(S) {
    return S.split('').reverse().join('');

}

Code: 12:59:00 UTC, js, autosave

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

function solution(S) {
    // write your code in JavaScript (Node.js 8.9.4)
    if (S.length % 2 === 0) {
        return -1;
    }
    if (S.length === 1) {
        return 0;
    }
    let mid = Math.floor(S.length / 2);
    let startString = S.slice(0, mid);
    let endString = reverseString(S.slice(mid+1));
    if (startString === endString) {
        return mid;
    }
    return -1;
}

function reverseString(S) {
    return S.split('').reverse().join('');

}

Code: 12:59:03 UTC, js, verify, result: Passed

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

function solution(S) {
    // write your code in JavaScript (Node.js 8.9.4)
    if (S.length % 2 === 0) {
        return -1;
    }
    if (S.length === 1) {
        return 0;
    }
    let mid = Math.floor(S.length / 2);
    let startString = S.slice(0, mid);
    let endString = reverseString(S.slice(mid+1));
    if (startString === endString) {
        return mid;
    }
    return -1;
}

function reverseString(S) {
    return S.split('').reverse().join('');

}

Analysis

expand all Example tests

▶

example1
first example

✔

0.068 s

▶

example2
second example

✔

0.068 s

Code: 12:59:15 UTC, js, verify, result: Passed

show code in pop-up

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

function solution(S) {
    // write your code in JavaScript (Node.js 8.9.4)
    if (S.length % 2 === 0) {
        return -1;
    }
    if (S.length === 1) {
        return 0;
    }
    let mid = Math.floor(S.length / 2);
    let startString = S.slice(0, mid);
    let endString = reverseString(S.slice(mid+1));
    if (startString === endString) {
        return mid;
    }
    return -1;
}

function reverseString(S) {
    return S.split('').reverse().join('');

}

User test case 1:

['']

User test case 2:

['not']

Analysis

expand all Example tests

▶

example1
first example

✔

0.068 s

▶

example2
second example

✔

0.068 s

expand all User tests

▶

test_data1

✔

0.068 s

OK
function result: -1

▶

test_data2

✔

0.072 s

OK
function result: -1

Code: 12:59:26 UTC, js, verify, result: Passed

show code in pop-up

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

function solution(S) {
    // write your code in JavaScript (Node.js 8.9.4)
    if (S.length % 2 === 0) {
        return -1;
    }
    if (S.length === 1) {
        return 0;
    }
    let mid = Math.floor(S.length / 2);
    let startString = S.slice(0, mid);
    let endString = reverseString(S.slice(mid+1));
    if (startString === endString) {
        return mid;
    }
    return -1;
}

function reverseString(S) {
    return S.split('').reverse().join('');

}

User test case 1:

['']

User test case 2:

['not']

Analysis

expand all Example tests

▶

example1
first example

✔

0.068 s

▶

example2
second example

✔

0.068 s

expand all User tests

▶

test_data1

✔

0.068 s

OK
function result: -1

▶

test_data2

✔

0.068 s

OK
function result: -1

Code: 12:59:28 UTC, js, final, score: 100

show code in pop-up

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

function solution(S) {
    // write your code in JavaScript (Node.js 8.9.4)
    if (S.length % 2 === 0) {
        return -1;
    }
    if (S.length === 1) {
        return 0;
    }
    let mid = Math.floor(S.length / 2);
    let startString = S.slice(0, mid);
    let endString = reverseString(S.slice(mid+1));
    if (startString === endString) {
        return mid;
    }
    return -1;
}

function reverseString(S) {
    return S.split('').reverse().join('');

}

Analysis summary

The solution obtained perfect score.

Analysis

Detected time complexity:

O(length(S))

expand all Example tests

▶

example1
first example

✔

0.068 s

▶

example2
second example

✔

0.068 s

expand all Correctness tests

▶

extreme_empty_or_one
empty or one character strings

✔

0.068 s

▶

symmetric
short symmetric strings

✔

0.068 s

0.072 s

▶

even
even length or symmetric strings

✔

0.068 s

0.076 s

▶

three_chars
3 characters (multiple runs)

✔

0.068 s

▶

letters_a
letters 'a' only

✔

0.072 s

0.068 s

▶

alphabet_symmetric
nontrivial symmetry, N = 51

✔

0.072 s

▶

nonsymmetric_inside
mismatch close to the middle, N = 43

✔

0.068 s

▶

nonsymmetric_outside
mismatch close to the ends, N = 43

✔

0.068 s

expand all Performance tests

▶

large_nonsymmetric
nonsymmetric string, N = 100k+ + [aba]

✔

0.076 s

0.080 s

0.068 s

▶

large_symmetric1
symmetric string, N=100k

✔

0.080 s

▶

large_symmetric2
symmetric string, N=200k

✔

0.084 s

▶

big_symmetric3
symmetric string, N=1M+

✔

0.152 s

▶

big_nonsymmetric
nonsymmetric string, N = ~1M

✔

0.156 s

0.148 s

0.068 s

▶

extreme_size
N = ~2M

✔

0.240 s

0.228 s

0.076 s

0.224 s