Test results - Codility

Tasks Details

easy

1. EquiLeader

Find the index S such that the leaders of the sequences A[0], A[1], ..., A[S] and A[S + 1], A[S + 2], ..., A[N - 1] are the same.

Task Score

100%

Correctness

100%

Performance

100%

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

The leader of this array is the value that occurs in more than half of the elements of A.

An equi leader is an index S such that 0 ≤ S < N − 1 and two sequences A[0], A[1], ..., A[S] and A[S + 1], A[S + 2], ..., A[N − 1] have leaders of the same value.

For example, given array A such that:

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

we can find two equi leaders:

0, because sequences: (4) and (3, 4, 4, 4, 2) have the same leader, whose value is 4.

2, because sequences: (4, 3, 4) and (4, 4, 2) have the same leader, whose value is 4.

The goal is to count the number of equi leaders.

Write a function:

int solution(vector<int> &A);

that, given a non-empty array A consisting of N integers, returns the number of equi leaders.

For example, given:

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

the function should return 2, as explained above.

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 [−1,000,000,000..1,000,000,000].

Solution

Programming language used C++

Time spent on task 4 minutes

Notes

not defined yet

Task timeline

Code: 16:20:37 UTC, java, autosave

show code in pop-up

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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: 16:20:39 UTC, cpp, autosave

show code in pop-up

1 2 3 4 5 6 7 8 9

// 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;

int solution(vector<int> &A) {
    // write your code in C++14 (g++ 6.2.0)
}

Code: 16:20:53 UTC, cpp, autosave

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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 25 26 27 28 29 30 31 32 33 34 35 36 37 38

// you can use includes, for example:
#include <map>
#include <iostream>
// you can write to stdout for debugging purposes, e.g.
// cout << "this is a debug message" << endl;

int solution(vector<int> &A) {
    // write your code in C++14 (g++ 6.2.0)
    
    map<int, int> m;
    int max = 0, index, result = 0, count = 0;
    
    for(int i = 0; i < A.size(); i++){
        if(m.find(A[i]) != m.end()){
            m[A[i]] += 1;
            if(max < m[A[i]]){
                max = m[A[i]];
                index = A[i];   
            }
        }else
            m.insert(pair<int, int>(A[i], 1));
    }
    
    if(max < A.size() / 2)
        return 0;
    
    for(int i = 0; i < A.size(); i++){
        if(A[i] == index){
            count++;
            m[index]--;
        }
        
        if(m[index] > (A.size() - (i + 1)) / 2 && count > i / 2)
                result++;
    }
    
    return result;
}

Code: 16:20:57 UTC, cpp, 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 25 26 27 28 29 30 31 32 33 34 35 36 37 38

// you can use includes, for example:
#include <map>
#include <iostream>
// you can write to stdout for debugging purposes, e.g.
// cout << "this is a debug message" << endl;

int solution(vector<int> &A) {
    // write your code in C++14 (g++ 6.2.0)
    
    map<int, int> m;
    int max = 0, index, result = 0, count = 0;
    
    for(int i = 0; i < A.size(); i++){
        if(m.find(A[i]) != m.end()){
            m[A[i]] += 1;
            if(max < m[A[i]]){
                max = m[A[i]];
                index = A[i];   
            }
        }else
            m.insert(pair<int, int>(A[i], 1));
    }
    
    if(max < A.size() / 2)
        return 0;
    
    for(int i = 0; i < A.size(); i++){
        if(A[i] == index){
            count++;
            m[index]--;
        }
        
        if(m[index] > (A.size() - (i + 1)) / 2 && count > i / 2)
                result++;
    }
    
    return result;
}

Analysis

expand all Example tests

▶

example
example test

✘

WRONG ANSWER
got 3 expected 2

0.001 s

WRONG ANSWER, got 3 expected 2

Code: 16:21:20 UTC, cpp, autosave

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 26 27 28 29 30 31 32 33 34 35 36 37 38

// you can use includes, for example:
#include <map>
#include <iostream>
// you can write to stdout for debugging purposes, e.g.
// cout << "this is a debug message" << endl;

int solution(vector<int> &A) {
    // write your code in C++14 (g++ 6.2.0)
    
    map<int, int> m;
    int max = 0, index, result = 0, count = 0;
    
    for(int i = 0; i < A.size(); i++){
        if(m.find(A[i]) != m.end()){
            m[A[i]] += 1;
            if(max < m[A[i]]){
                max = m[A[i]];
                index = A[i];   
            }
        }else
            m.insert(pair<int, int>(A[i], 1));
    }
    
    if(max < A.size() / 2)
        return 0;
    
    for(int i = 0; i < A.size(); i++){
        if(A[i] == index){
            count++;
            m[index]--;
        }
        
        if(m[index] > (A.size() - (i + 1)) / 2 && count > i / 2)
            result++;
    }
    
    return result;
}

Code: 16:22:43 UTC, cpp, autosave

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 26 27 28 29 30 31 32 33 34 35 36 37 38

// you can use includes, for example:
#include <map>
#include <iostream>
// you can write to stdout for debugging purposes, e.g.
// cout << "this is a debug message" << endl;

int solution(vector<int> &A) {
    // write your code in C++14 (g++ 6.2.0)
    
    map<int, int> m;
    int max = 0, index, result = 0, count = 0;
    
    for(int i = 0; i < A.size(); i++){
        if(m.find(A[i]) != m.end()){
            m[A[i]] += 1;
            if(max < m[A[i]]){
                max = m[A[i]];
                index = A[i];   
            }
        }else
            m.insert(pair<int, int>(A[i], 1));
    }
    
    if(max < A.size() / 2)
        return 0;
    
    for(int i = 0; i < A.size(); i++){
        if(A[i] == index){
            count++;
            m[index]--;
        }
        
        if(m[index] > (A.size() - (i + 1)) / 2 && count > i / 2){
            result++;
    }
    
    return result;
}

Code: 16:22:53 UTC, cpp, autosave

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 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40

// you can use includes, for example:
#include <map>
#include <iostream>
// you can write to stdout for debugging purposes, e.g.
// cout << "this is a debug message" << endl;

int solution(vector<int> &A) {
    // write your code in C++14 (g++ 6.2.0)
    
    map<int, int> m;
    int max = 0, index, result = 0, count = 0;
    
    for(int i = 0; i < A.size(); i++){
        if(m.find(A[i]) != m.end()){
            m[A[i]] += 1;
            if(max < m[A[i]]){
                max = m[A[i]];
                index = A[i];   
            }
        }else
            m.insert(pair<int, int>(A[i], 1));
    }
    
    if(max < A.size() / 2)
        return 0;
    
    for(int i = 0; i < A.size(); i++){
        if(A[i] == index){
            count++;
            m[index]--;
        }
        
        if(m[index] > (A.size() - (i + 1)) / 2 && count > i / 2){
            result++;
            cout <<    
        }
    }
    
    return result;
}

Code: 16:22:59 UTC, cpp, verify, result: Failed

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 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40

// you can use includes, for example:
#include <map>
#include <iostream>
// you can write to stdout for debugging purposes, e.g.
// cout << "this is a debug message" << endl;

int solution(vector<int> &A) {
    // write your code in C++14 (g++ 6.2.0)
    
    map<int, int> m;
    int max = 0, index, result = 0, count = 0;
    
    for(int i = 0; i < A.size(); i++){
        if(m.find(A[i]) != m.end()){
            m[A[i]] += 1;
            if(max < m[A[i]]){
                max = m[A[i]];
                index = A[i];   
            }
        }else
            m.insert(pair<int, int>(A[i], 1));
    }
    
    if(max < A.size() / 2)
        return 0;
    
    for(int i = 0; i < A.size(); i++){
        if(A[i] == index){
            count++;
            m[index]--;
        }
        
        if(m[index] > (A.size() - (i + 1)) / 2 && count > i / 2){
            result++;
            cout << m[index] << endl;   
        }
    }
    
    return result;
}

Analysis

expand all Example tests

▶

example
example test

✘

WRONG ANSWER
got 3 expected 2

0.001 s

WRONG ANSWER, got 3 expected 2

stdout:

3
3
2

Code: 16:23:42 UTC, cpp, autosave

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 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40

// you can use includes, for example:
#include <map>
#include <iostream>
// you can write to stdout for debugging purposes, e.g.
// cout << "this is a debug message" << endl;

int solution(vector<int> &A) {
    // write your code in C++14 (g++ 6.2.0)
    
    map<int, int> m;
    int max = 0, index, result = 0, count = 0;
    
    for(int i = 0; i < A.size(); i++){
        if(m.find(A[i]) != m.end()){
            m[A[i]] += 1;
            if(max < m[A[i]]){
                max = m[A[i]];
                index = A[i];   
            }
        }else
            m.insert(pair<int, int>(A[i], 1));
    }
    
    if(max < A.size() / 2)
        return 0;
    
    for(int i = 0; i < A.size(); i++){
        if(A[i] == index){
            count++;
            m[index]--;
        }
        
        if(m[index] > (A.size() - (i + 1)) / 2 && count > (i / 2){
            result++;
            cout << m[index] << endl;   
        }
    }
    
    return result;
}

Code: 16:23:46 UTC, cpp, verify, result: Passed

show code in pop-up

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// you can use includes, for example:
#include <map>
#include <iostream>
// you can write to stdout for debugging purposes, e.g.
// cout << "this is a debug message" << endl;

int solution(vector<int> &A) {
    // write your code in C++14 (g++ 6.2.0)
    
    map<int, int> m;
    int max = 0, index, result = 0, count = 0;
    
    for(int i = 0; i < A.size(); i++){
        if(m.find(A[i]) != m.end()){
            m[A[i]] += 1;
            if(max < m[A[i]]){
                max = m[A[i]];
                index = A[i];   
            }
        }else
            m.insert(pair<int, int>(A[i], 1));
    }
    
    if(max < A.size() / 2)
        return 0;
    
    for(int i = 0; i < A.size(); i++){
        if(A[i] == index){
            count++;
            m[index]--;
        }
        
        if(m[index] > (A.size() - (i + 1)) / 2 && count > (i + 1) / 2){
            result++;
            cout << m[index] << endl;   
        }
    }
    
    return result;
}

Analysis

expand all Example tests

▶

example
example test

✔

0.001 s

stdout:

3
2

Code: 16:23:55 UTC, cpp, 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 26 27 28 29 30 31 32 33 34 35 36 37 38 39

// you can use includes, for example:
#include <map>
#include <iostream>
// you can write to stdout for debugging purposes, e.g.
// cout << "this is a debug message" << endl;

int solution(vector<int> &A) {
    // write your code in C++14 (g++ 6.2.0)
    
    map<int, int> m;
    int max = 0, index, result = 0, count = 0;
    
    for(int i = 0; i < A.size(); i++){
        if(m.find(A[i]) != m.end()){
            m[A[i]] += 1;
            if(max < m[A[i]]){
                max = m[A[i]];
                index = A[i];   
            }
        }else
            m.insert(pair<int, int>(A[i], 1));
    }
    
    if(max < A.size() / 2)
        return 0;
    
    for(int i = 0; i < A.size(); i++){
        if(A[i] == index){
            count++;
            m[index]--;
        }
        
        if(m[index] > (A.size() - (i + 1)) / 2 && count > (i + 1) / 2)
            result++;
        
    }
    
    return result;
}

Analysis

expand all Example tests

▶

example
example test

✔

0.001 s

Code: 16:23:59 UTC, cpp, 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 26 27 28 29 30 31 32 33 34 35 36 37 38 39

// you can use includes, for example:
#include <map>
#include <iostream>
// you can write to stdout for debugging purposes, e.g.
// cout << "this is a debug message" << endl;

int solution(vector<int> &A) {
    // write your code in C++14 (g++ 6.2.0)
    
    map<int, int> m;
    int max = 0, index, result = 0, count = 0;
    
    for(int i = 0; i < A.size(); i++){
        if(m.find(A[i]) != m.end()){
            m[A[i]] += 1;
            if(max < m[A[i]]){
                max = m[A[i]];
                index = A[i];   
            }
        }else
            m.insert(pair<int, int>(A[i], 1));
    }
    
    if(max < A.size() / 2)
        return 0;
    
    for(int i = 0; i < A.size(); i++){
        if(A[i] == index){
            count++;
            m[index]--;
        }
        
        if(m[index] > (A.size() - (i + 1)) / 2 && count > (i + 1) / 2)
            result++;
        
    }
    
    return result;
}

Analysis

expand all Example tests

▶

example
example test

✔

0.001 s

Code: 16:24:02 UTC, cpp, 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 26 27 28 29 30 31 32 33 34 35 36 37 38 39

// you can use includes, for example:
#include <map>
#include <iostream>
// you can write to stdout for debugging purposes, e.g.
// cout << "this is a debug message" << endl;

int solution(vector<int> &A) {
    // write your code in C++14 (g++ 6.2.0)
    
    map<int, int> m;
    int max = 0, index, result = 0, count = 0;
    
    for(int i = 0; i < A.size(); i++){
        if(m.find(A[i]) != m.end()){
            m[A[i]] += 1;
            if(max < m[A[i]]){
                max = m[A[i]];
                index = A[i];   
            }
        }else
            m.insert(pair<int, int>(A[i], 1));
    }
    
    if(max < A.size() / 2)
        return 0;
    
    for(int i = 0; i < A.size(); i++){
        if(A[i] == index){
            count++;
            m[index]--;
        }
        
        if(m[index] > (A.size() - (i + 1)) / 2 && count > (i + 1) / 2)
            result++;
        
    }
    
    return result;
}

Analysis summary

The solution obtained perfect score.

Analysis

Detected time complexity:

O(N)

expand all Example tests

▶

example
example test

✔

0.001 s

expand all Correctness tests

▶

single
single element

✔

0.001 s

▶

double
two elements

✔

0.001 s

▶

simple
simple test

✔

0.001 s

▶

small_random
small random test with two values, length = ~100

✔

0.001 s

▶

small
random + 200 * [MIN_INT] + random ,length = ~300

✔

0.001 s

expand all Performance tests

▶

large_random
large random test with two values, length = ~50,000

✔

0.004 s

▶

large
random(0,1) + 50000 * [0] + random(0, 1), length = ~100,000

✔

0.004 s

▶

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

✔

0.040 s

0.001 s

▶

extreme_large
all the same values

✔

0.012 s