Test results - Codility

Tasks Details

easy

1. PermCheck

Check whether array A is a permutation.

100%

A non-empty array A consisting of N integers is given.

A permutation is a sequence containing each element from 1 to N once, and only once.

For example, array A such that:

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

is a permutation, but array A such that:

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

is not a permutation, because value 2 is missing.

The goal is to check whether array A is a permutation.

Write a function:

int solution(vector<int> &A);

that, given an array A, returns 1 if array A is a permutation and 0 if it is not.

For example, given array A such that:

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

the function should return 1.

Given array A such that:

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

the function should return 0.

Write an efficient algorithm for the following assumptions:

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

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

Solution

Programming language used C++

Time spent on task 1 minutes

Notes

not defined yet

Task timeline

Code: 10:16:37 UTC, cpp, verify, result: Passed

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 26 27

// you can use includes, for example:
// #include <algorithm>

// you can write to stdout for debugging purposes, e.g.
// cout << "this is a debug message" << endl;
#include <bitset>
#define SIZEA 1000000000
int solution(vector<int> &A) {
  
  auto pbits = new bitset<SIZEA>;
  pbits->reset();
  for (size_t i = 0; i < A.size(); i++) {
    int el = A[i];
    
    if ((*pbits)[el]) {
      return 0;
    }
    (*pbits)[el] = true;
  }
  for (uint i = 0; i < A.size(); i++) {

    if (!(*pbits)[i+1]) {
      return 0;
    }
  }
  return 1;
}

Analysis

▶

example1
the first example test

✔

▶

example2
the second example test

✔

Code: 10:16:46 UTC, cpp, verify, result: Passed

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 26 27

// you can use includes, for example:
// #include <algorithm>

// you can write to stdout for debugging purposes, e.g.
// cout << "this is a debug message" << endl;
#include <bitset>
#define SIZEA 1000000000
int solution(vector<int> &A) {
  
  auto pbits = new bitset<SIZEA>;
  pbits->reset();
  for (size_t i = 0; i < A.size(); i++) {
    int el = A[i];
    
    if ((*pbits)[el]) {
      return 0;
    }
    (*pbits)[el] = true;
  }
  for (uint i = 0; i < A.size(); i++) {

    if (!(*pbits)[i+1]) {
      return 0;
    }
  }
  return 1;
}

Analysis

▶

example1
the first example test

✔

▶

example2
the second example test

✔

Code: 10:16:50 UTC, cpp, final, score: 100

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 26 27

// you can use includes, for example:
// #include <algorithm>

// you can write to stdout for debugging purposes, e.g.
// cout << "this is a debug message" << endl;
#include <bitset>
#define SIZEA 1000000000
int solution(vector<int> &A) {
  
  auto pbits = new bitset<SIZEA>;
  pbits->reset();
  for (size_t i = 0; i < A.size(); i++) {
    int el = A[i];
    
    if ((*pbits)[el]) {
      return 0;
    }
    (*pbits)[el] = true;
  }
  for (uint i = 0; i < A.size(); i++) {

    if (!(*pbits)[i+1]) {
      return 0;
    }
  }
  return 1;
}

Analysis summary

The solution obtained perfect score.

Analysis

Detected time complexity:

O(N) or O(N * log(N))

▶

example1
the first example test

✔

▶

example2
the second example test

✔

▶

extreme_min_max
single element with minimal/maximal value

✔

▶

single
single element

✔

▶

double
two elements

✔

▶

antiSum1
total sum is correct, but it is not a permutation, N <= 10

✔

▶

small_permutation
permutation + one element occurs twice, N = ~100

✔

▶

permutations_of_ranges
permutations of sets like [2..100] for which the anwsers should be false

✔

▶

medium_permutation
permutation + few elements occur twice, N = ~10,000

✔

▶

antiSum2
total sum is correct, but it is not a permutation, N = ~100,000

✔

▶

large_not_permutation
permutation + one element occurs three times, N = ~100,000

✔

▶

large_range
sequence 1, 2, ..., N, N = ~100,000

✔

▶

extreme_values
all the same values, N = ~100,000

✔

▶

various_permutations
all sequences are permutations

✔