Tasks Details
hard
1.
WinterLights
Given a string of digits, count the number of subwords (consistent subsequences) that are anagrams of any palindrome.
Task Score
30%
Correctness
100%
Performance
12%
Winter is coming and Victor is going to buy some new lights. In the store, lights are available in 10 colors, numbered from 0 to 9. They are connected together in a huge chain. Victor can choose any single segment of the chain and buy it.
This task would be easy if it weren't for Victor's ambition. He wants to outdo his neighbors with some truly beautiful lights, so the chain has to look the same from both its left and right sides (so that both neighbors see the same effect).
Victor is a mechanic, so after buying a segment of the chain, he can rearrange its lights in any order he wants. However, now he has to buy a chain segment that will satisfy above condition when its lights are reordered. Can you compute how many possible segments he can choose from?
Write a function:
class Solution { public int solution(string S); }
that, given a description of the chain of lights, returns the number of segments that Victor can buy modulo 1,000,000,007. The chain is represented by a string of digits (characters from '0' to '9') of length N. The digits represent the colors of the lights. Victor can only buy a segment of the chain in which he can reorder the lights such that the chain will look identical from both the left and right sides (i.e. when reversed).
For example, given:
S = "02002"the function should return 11. Victor can buy the following segments of the chain:
"0", "2", "0", "0", "2", "00", "020", "200", "002", "2002", "02002"Note that a segment comprising a single "0" is counted three times: first it describes the subchain consisting of only the first light, then the subchain consisting of the third light and finally the subchain consisting of the fourth light. Also note that Victor can buy the whole chain ("02002"), as, after swapping the first two lights, it would become "20002", which is the same when seen from both from left and right.
Write an efficient algorithm for the following assumptions:
- string S is made only of digits (0−9);
- the length of string S is within the range [1..200,000].
Copyright 2009–2025 by Codility Limited. All Rights Reserved. Unauthorized copying, publication or disclosure prohibited.
Solution
Programming language used C#
Time spent on task 1 minutes
Notes
not defined yet
Code: 17:26:28 UTC,
cs,
verify,
result: Passed
123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172
using System;
using System.Collections.Generic;
using System.Linq;
// you can also use other imports, for example:
// using System.Collections.Generic;
// you can write to stdout for debugging purposes, e.g.
// Console.WriteLine("this is a debug message");
class Solution {
public int solution(string S) {
// write your code in C# 6.0 with .NET 4.5 (Mono)
return TotalChains(S);
}
static bool CanBePalindrome(string input)
{
List<int> list = new List<int>();
bool isEvenlength = input.Length % 2 == 0 ? true : false;
bool canBePalindrome = false;
foreach (char ch in input)
{
list.Add(Convert.ToInt16(ch) - 48);
}
var result = list.GroupBy(r => r)
.Select(r => new
{
Data = r.Key,
Count = r.Count()
});
if (isEvenlength)
{
canBePalindrome = result.Where(x => x.Count % 2 != 0).Count() > 0 ? false : true;
}
else
{
canBePalindrome = result.Where(x => x.Count % 2 != 0).Count() == 1 ? true : false;
}
return canBePalindrome;
}
static int TotalChains(string input)
{
int totalPossibleChains = input.Length;
int startIndex = 0;
int counter = input.Length;
while (counter >= 2)
{
int temp = counter;
int window = temp;
for (int i = temp; temp <= input.Length; temp++, startIndex++)
{
if (CanBePalindrome(input.Substring(startIndex, window)))
{
totalPossibleChains++;
}
}
counter--;
startIndex = 0;
}
// Console.WriteLine(totalPossibleChains);
// foreach(string s in allPossibilites)
// Console.WriteLine(s);
return totalPossibleChains;
}
}
Analysis
Code: 17:26:34 UTC,
cs,
verify,
result: Passed
123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172
using System;
using System.Collections.Generic;
using System.Linq;
// you can also use other imports, for example:
// using System.Collections.Generic;
// you can write to stdout for debugging purposes, e.g.
// Console.WriteLine("this is a debug message");
class Solution {
public int solution(string S) {
// write your code in C# 6.0 with .NET 4.5 (Mono)
return TotalChains(S);
}
static bool CanBePalindrome(string input)
{
List<int> list = new List<int>();
bool isEvenlength = input.Length % 2 == 0 ? true : false;
bool canBePalindrome = false;
foreach (char ch in input)
{
list.Add(Convert.ToInt16(ch) - 48);
}
var result = list.GroupBy(r => r)
.Select(r => new
{
Data = r.Key,
Count = r.Count()
});
if (isEvenlength)
{
canBePalindrome = result.Where(x => x.Count % 2 != 0).Count() > 0 ? false : true;
}
else
{
canBePalindrome = result.Where(x => x.Count % 2 != 0).Count() == 1 ? true : false;
}
return canBePalindrome;
}
static int TotalChains(string input)
{
int totalPossibleChains = input.Length;
int startIndex = 0;
int counter = input.Length;
while (counter >= 2)
{
int temp = counter;
int window = temp;
for (int i = temp; temp <= input.Length; temp++, startIndex++)
{
if (CanBePalindrome(input.Substring(startIndex, window)))
{
totalPossibleChains++;
}
}
counter--;
startIndex = 0;
}
// Console.WriteLine(totalPossibleChains);
// foreach(string s in allPossibilites)
// Console.WriteLine(s);
return totalPossibleChains;
}
}
Analysis
Code: 17:26:39 UTC,
cs,
final,
score:
30
123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172
using System;
using System.Collections.Generic;
using System.Linq;
// you can also use other imports, for example:
// using System.Collections.Generic;
// you can write to stdout for debugging purposes, e.g.
// Console.WriteLine("this is a debug message");
class Solution {
public int solution(string S) {
// write your code in C# 6.0 with .NET 4.5 (Mono)
return TotalChains(S);
}
static bool CanBePalindrome(string input)
{
List<int> list = new List<int>();
bool isEvenlength = input.Length % 2 == 0 ? true : false;
bool canBePalindrome = false;
foreach (char ch in input)
{
list.Add(Convert.ToInt16(ch) - 48);
}
var result = list.GroupBy(r => r)
.Select(r => new
{
Data = r.Key,
Count = r.Count()
});
if (isEvenlength)
{
canBePalindrome = result.Where(x => x.Count % 2 != 0).Count() > 0 ? false : true;
}
else
{
canBePalindrome = result.Where(x => x.Count % 2 != 0).Count() == 1 ? true : false;
}
return canBePalindrome;
}
static int TotalChains(string input)
{
int totalPossibleChains = input.Length;
int startIndex = 0;
int counter = input.Length;
while (counter >= 2)
{
int temp = counter;
int window = temp;
for (int i = temp; temp <= input.Length; temp++, startIndex++)
{
if (CanBePalindrome(input.Substring(startIndex, window)))
{
totalPossibleChains++;
}
}
counter--;
startIndex = 0;
}
// Console.WriteLine(totalPossibleChains);
// foreach(string s in allPossibilites)
// Console.WriteLine(s);
return totalPossibleChains;
}
}Analysis summary
The following issues have been detected: timeout errors.
Analysis
Detected time complexity:
O(N**3)
expand all
Correctness tests
1.
0.055 s
OK
2.
0.055 s
OK
3.
0.070 s
OK
4.
0.069 s
OK
1.
0.073 s
OK
2.
0.070 s
OK
3.
0.070 s
OK
4.
0.070 s
OK
5.
0.071 s
OK
6.
0.070 s
OK
expand all
Performance tests
1.
0.105 s
OK
2.
0.089 s
OK
big_correctness
big correctness tests (length = 300)
big correctness tests (length = 300)
✘
TIMEOUT ERROR
running time: 0.57 sec., time limit: 0.22 sec.
running time: 0.57 sec., time limit: 0.22 sec.
1.
0.567 s
TIMEOUT ERROR,
running time: 0.57 sec., time limit: 0.22 sec.
2.
0.427 s
TIMEOUT ERROR,
running time: 0.43 sec., time limit: 0.22 sec.
big_correctness1
big correctness tests (length = 1000)
big correctness tests (length = 1000)
✘
TIMEOUT ERROR
running time: >6.00 sec., time limit: 0.21 sec.
running time: >6.00 sec., time limit: 0.21 sec.
1.
6.000 s
TIMEOUT ERROR,
running time: >6.00 sec., time limit: 0.21 sec.
2.
6.000 s
TIMEOUT ERROR,
running time: >6.00 sec., time limit: 0.22 sec.
large_correctness
large correctness tests (length = 50 000)
large correctness tests (length = 50 000)
✘
TIMEOUT ERROR
running time: >6.00 sec., time limit: 0.26 sec.
running time: >6.00 sec., time limit: 0.26 sec.
1.
6.000 s
TIMEOUT ERROR,
running time: >6.00 sec., time limit: 0.26 sec.
2.
6.000 s
TIMEOUT ERROR,
running time: >6.00 sec., time limit: 0.25 sec.
max_correctness
max correctness tests (length = 200 000)
max correctness tests (length = 200 000)
✘
TIMEOUT ERROR
running time: >6.00 sec., time limit: 0.33 sec.
running time: >6.00 sec., time limit: 0.33 sec.
1.
6.000 s
TIMEOUT ERROR,
running time: >6.00 sec., time limit: 0.33 sec.
2.
6.000 s
TIMEOUT ERROR,
running time: >6.00 sec., time limit: 0.32 sec.
large_random_increasing
tests with increasing value of N and varying alphabet size
tests with increasing value of N and varying alphabet size
✘
TIMEOUT ERROR
running time: >6.00 sec., time limit: 0.23 sec.
running time: >6.00 sec., time limit: 0.23 sec.
1.
6.000 s
TIMEOUT ERROR,
running time: >6.00 sec., time limit: 0.23 sec.
2.
6.000 s
TIMEOUT ERROR,
running time: >6.00 sec., time limit: 0.25 sec.
3.
6.000 s
TIMEOUT ERROR,
running time: >6.00 sec., time limit: 0.33 sec.
4.
6.000 s
TIMEOUT ERROR,
running time: >6.00 sec., time limit: 0.33 sec.
int64
tests detecting lack of int64 in solutions
tests detecting lack of int64 in solutions
✘
TIMEOUT ERROR
running time: >6.00 sec., time limit: 0.34 sec.
running time: >6.00 sec., time limit: 0.34 sec.
1.
6.000 s
TIMEOUT ERROR,
running time: >6.00 sec., time limit: 0.34 sec.
2.
6.000 s
TIMEOUT ERROR,
running time: >6.00 sec., time limit: 0.33 sec.
special_words
tests introducting special words, e.g. Fibonacci, Thue-Morse, Gray codes
tests introducting special words, e.g. Fibonacci, Thue-Morse, Gray codes
✘
TIMEOUT ERROR
running time: >6.00 sec., time limit: 0.33 sec.
running time: >6.00 sec., time limit: 0.33 sec.
1.
6.000 s
TIMEOUT ERROR,
running time: >6.00 sec., time limit: 0.33 sec.
2.
6.000 s
TIMEOUT ERROR,
running time: >6.00 sec., time limit: 0.25 sec.
3.
6.000 s
TIMEOUT ERROR,
running time: >6.00 sec., time limit: 0.28 sec.