HackerRank Migratory Birds Problem Solution

In this post, We are going to solve HackerRank Migratory Birds Problem. Given an array of bird sightings where every element represents a bird type id, determine the id of the most frequently sighted type. If more than 1 type has been spotted that maximum amount, return the smallest of their ids.

Example

arr = [1, 1, 2, 2, 3]

There are two each of types 1 and 2, and one sighting of type 3. Pick the lower of the two types seen twice: type 1.

Function Description

Complete the migratory birds function in the editor below.

migratory birds have the following parameter(s):

int arr[n]: the types of birds sighted

Returns

int: the lowest type id of the most frequently sighted birds

Input Format

The first line contains an integer, n, the size of arr.
The second line describes arr as n space-separated integers, each a type number of the bird sighted.

Constraints

5 < n < 2 X 10 power 5
It is guaranteed that each type is 1,2, 3, 4, or 5.

Sample Input 0

6
1 4 4 4 5 3

Sample Output 0

Explanation 0

The different types of birds occur in the following frequencies:

Type 1:1 bird
Type 2:0 birds
Type 3:1 bird
Type 4:3 birds
Type 5:1 bird

The type number that occurs at the highest frequency types 4, so we print 4 as our answer.

Sample Input 1

11
1 2 3 4 5 4 3 2 1 3 4

Sample Output 1

Explanation 1

The different types of birds occur in the following frequencies:

Type 1: 2
Type 2: 2
Type 3: 3
Type 4: 3
Type 5: 1

Two types have a frequency of 3, and the lower of those are type 3.

HackerRank Migratory Birds Problem Solution

Migratory Birds C Solution

#include <math.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <assert.h>
#include <limits.h>
#include <stdbool.h>

int main(){
    int n; 
    scanf("%d",&n);
    int *types = malloc(sizeof(int) * n);
    for(int types_i = 0; types_i < n; types_i++){
       scanf("%d",&types[types_i]);
    }
    
    int counts[5];
    for(int i=0; i<5; i++){
        counts[i] =0;
    }
    
    for(int i=0; i<n; i++){
        counts[types[i]-1]++;
    }
    
    int maxpos = 0;
    for(int i=1; i<5; i++){
        if(counts[i] > counts[maxpos]){
            maxpos = i;
        }
    }
    printf("%d\n",maxpos+1);
    return 0;
}

Migratory Birds C++ Solution

#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;


int main(){
    int num_of_birds, best_bird = 1, max_bird = 0;
    cin >> num_of_birds;
    vector<int> types(5, 0);
    for(int i = 0, next_bird; i < num_of_birds; ++i){
        cin >> next_bird;
        ++types[next_bird-1];
    }
    
    for(int i = 0; i < 5; ++i){
        if(types[i] > max_bird){
            max_bird = types[i];
            best_bird = i + 1;
        }
    }
    cout << best_bird << endl;
    return 0;
}

Migratory Birds C Sharp Solution

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
class Solution {

    static void Main(String[] args) {
        int n = Convert.ToInt32(Console.ReadLine());
        string[] types_temp = Console.ReadLine().Split(' ');
        int[] types = Array.ConvertAll(types_temp,Int32.Parse);
        // your code goes here
        var arr = new int[5];
        for (var i = 0; i < n; i++){
            arr[types[i]-1] = arr[types[i]-1] + 1;
        }
        var result = 4;
        for(var i = 3; i >= 0; i--){
            if(arr[i] >= arr[result]){
                result = i;
            }
        }
        Console.WriteLine(result + 1);
    }
}

Migratory Birds Java Solution

import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;
import java.util.function.Function;
import java.util.stream.Collectors;
import java.util.stream.IntStream;

public class Solution {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        int[] types = new int[n];
        for(int types_i=0; types_i < n; types_i++){
            types[types_i] = in.nextInt();
        }
        // your code goes here
        
        Map<Integer, Long> typesToCountMap = IntStream.of(types).
                boxed().
                collect(Collectors.groupingBy(Function.identity(), Collectors.counting()));


        Long maxCount = typesToCountMap.values().stream().
                max(Comparator.naturalOrder()).
                get();

        List<Integer> typeWithMaxCount = typesToCountMap.entrySet().stream().
                filter(item -> Objects.equals(item.getValue(), maxCount)).
                map(Map.Entry::getKey).
                collect(Collectors.toList());
        System.out.println(typeWithMaxCount.get(0));
    }
}

Migratory Birds JavaScript Solution

process.stdin.resume();
process.stdin.setEncoding('ascii');

var input_stdin = "";
var input_stdin_array = "";
var input_currentline = 0;

process.stdin.on('data', function (data) {
    input_stdin += data;
});

process.stdin.on('end', function () {
    input_stdin_array = input_stdin.split("\n");
    main();    
});

function readLine() {
    return input_stdin_array[input_currentline++];
}

/////////////// ignore above this line ////////////////////

function main() {
    var n = parseInt(readLine());
    types = readLine().split(' ');
    types = types.map(Number);
    // your code goes here
    
    var obj = {
        1:0,
        2:0,
        3:0,
        4:0,
        5:0
    }
    
    function count(num){
        obj[num]++;
    }
    
    types = types.map(count);
    
    var max = 0;
    var type = 1;
    
    for(var prop in obj){
        if(obj[prop]>max){
            max=obj[prop];
            type = prop;
        }else if(obj[prop]===max && prop<type){
            type=prop;
        }
    }
    
    console.log(type);
    
    

}

Migratory Birds Python Solution

#!/bin/python3

import sys


n = int(input().strip())
types = list(map(int, input().strip().split(' ')))
# your code goes here
counts = [0,0,0,0,0,0]
for i in types:
    counts[i]+=1;
print(counts.index(max(counts)))

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