Algorithm

Problem Name: Mathematics - Connecting Towns

Problem Link: https://www.hackerrank.com/challenges/connecting-towns/problem?isFullScreen=true

In this HackerRank in Mathematics - Connecting Towns solutions,

Cities on a map are connected by a number of roads. The number of roads between each city is in an array and city 0 is the starting location. The number of roads from city 0 to city 1 is the first value in the array, from city 1 to city 2 is the second, and so on.

How many paths are there from city to the last city in the list, modulo 1234567?

Example

n = 4

routes = [3,4,5]

There are 3 roads to city 1,4 roads to city 2 and 5 roads to city 3. The total number of roads is 3 * 4 * 5 mod 1234567 = 60

Note
Pass all the towns Ti for i=1 to n-1 in numerical order to reach Tn.

Function Description

Complete the connectingTowns function in the editor below.

connectingTowns has the following parameters:

  • int n: the number of towns
  • int routes[n-1]: the number of routes between towns

Returns

  • int: the total number of routes, modulo 1234567.

Input Format
The first line contains an integer T, T test-cases follow.

Each test-case has 2 lines.
The first line contains an integer N (the number of towns).
The second line contains N - 1 space separated integers where the ith integer denotes the number of routes, Ni, from the town Ti to Ti+1

Constraints
1 <= T<=1000
2< N <=100
1 <= routes[i] <=1000

Sample Input

2
3
1 3
4
2 2 2

Sample Output

3
8

Explanation
Case 1: 1 route from T1 to T2, 3 routes from T2 to T3, hence only 3 routes.
Case 2: There are 2 routes from each city to the next, hence 2 * 2 * 2 = 8.

 

 

Code Examples

#1 Code Example with C Programming

Code - C Programming


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

char* readline();
char* ltrim(char*);
char* rtrim(char*);
char** split_string(char*);

int parse_int(char*);

/*
 * Complete the 'connectingTowns' function below.
 *
 * The function is expected to return an INTEGER.
 * The function accepts following parameters:
 *  1. INTEGER n
 *  2. INTEGER_ARRAY routes
 */

int main(){
int n,routes_count,c;
    scanf("%d",&n);
    for(int i=0;i < n;i++){
    scanf("%d",&routes_count);
    int mul=1;
    for(int k=0;k < routes_count-1;k++){
        scanf("%d",&c);
        mul=(c*mul)%1234567;
        c=0;
        }
    printf("%d\n",mul);
    }
return 0;
}

char* readline() {
    size_t alloc_length = 1024;
    size_t data_length = 0;

    char* data = malloc(alloc_length);

    while (true) {
        char* cursor = data + data_length;
        char* line = fgets(cursor, alloc_length - data_length, stdin);

        if (!line) {
            break;
        }

        data_length += strlen(cursor);

        if (data_length  <  alloc_length - 1 || data[data_length - 1] == '\n') {
            break;
        }

        alloc_length <<= 1;

        data = realloc(data, alloc_length);

        if (!data) {
            data = '\0';

            break;
        }
    }

    if (data[data_length - 1] == '\n') {
        data[data_length - 1] = '\0';

        data = realloc(data, data_length);

        if (!data) {
            data = '\0';
        }
    } else {
        data = realloc(data, data_length + 1);

        if (!data) {
            data = '\0';
        } else {
            data[data_length] = '\0';
        }
    }

    return data;
}

char* ltrim(char* str) {
    if (!str) {
        return '\0';
    }

    if (!*str) {
        return str;
    }

    while (*str != '\0' && isspace(*str)) {
        str++;
    }

    return str;
}

char* rtrim(char* str) {
    if (!str) {
        return '\0';
    }

    if (!*str) {
        return str;
    }

    char* end = str + strlen(str) - 1;

    while (end >= str && isspace(*end)) {
        end--;
    }

    *(end + 1) = '\0';

    return str;
}

char** split_string(char* str) {
    char** splits = NULL;
    char* token = strtok(str, " ");

    int spaces = 0;

    while (token) {
        splits = realloc(splits, sizeof(char*) * ++spaces);

        if (!splits) {
            return splits;
        }

        splits[spaces - 1] = token;

        token = strtok(NULL, " ");
    }

    return splits;
}

int parse_int(char* str) {
    char* endptr;
    int value = strtol(str, &endptr, 10);

    if (endptr == str || *endptr != '\0') {
        exit(EXIT_FAILURE);
    }

    return value;
}
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#2 Code Example with C++ Programming

Code - C++ Programming


#include <bits/stdc++.h>

using namespace std;

string ltrim(const string &);
string rtrim(const string &);
vector < string> split(const string &);

/*
 * Complete the 'connectingTowns' function below.
 *
 * The function is expected to return an INTEGER.
 * The function accepts following parameters:
 *  1. INTEGER n
 *  2. INTEGER_ARRAY routes
 */

int connectingTowns(int n, vector<int> routes) {
    long utak=1;
    for(int i=0;i < =n-2;i++){
       utak= (utak*routes[i])%1234567;
    }
    return (utak);
}

int main()
{
    ofstream fout(getenv("OUTPUT_PATH"));

    string t_temp;
    getline(cin, t_temp);

    int t = stoi(ltrim(rtrim(t_temp)));

    for (int t_itr = 0; t_itr  <  t; t_itr++) {
        string n_temp;
        getline(cin, n_temp);

        int n = stoi(ltrim(rtrim(n_temp)));

        string routes_temp_temp;
        getline(cin, routes_temp_temp);

        vector < string> routes_temp = split(rtrim(routes_temp_temp));

        vector<int> routes(n - 1);

        for (int i = 0; i  <  n - 1; i++) {
            int routes_item = stoi(routes_temp[i]);

            routes[i] = routes_item;
        }

        int result = connectingTowns(n, routes);

        fout << result << "\n";
    }

    fout.close();

    return 0;
}

string ltrim(const string &str) {
    string s(str);

    s.erase(
        s.begin(),
        find_if(s.begin(), s.end(), not1(ptr_fun < int, int>(isspace)))
    );

    return s;
}

string rtrim(const string &str) {
    string s(str);

    s.erase(
        find_if(s.rbegin(), s.rend(), not1(ptr_fun < int, int>(isspace))).base(),
        s.end()
    );

    return s;
}

vector < string> split(const string &str) {
    vector<string> tokens;

    string::size_type start = 0;
    string::size_type end = 0;

    while ((end = str.find(" ", start)) != string::npos) {
        tokens.push_back(str.substr(start, end - start));

        start = end + 1;
    }

    tokens.push_back(str.substr(start));

    return tokens;
}
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#3 Code Example with C# Programming

Code - C# Programming


using System.CodeDom.Compiler;
using System.Collections.Generic;
using System.Collections;
using System.ComponentModel;
using System.Diagnostics.CodeAnalysis;
using System.Globalization;
using System.IO;
using System.Linq;
using System.Reflection;
using System.Runtime.Serialization;
using System.Text.RegularExpressions;
using System.Text;
using System;

class Result
{

    /*
     * Complete the 'connectingTowns' function below.
     *
     * The function is expected to return an INTEGER.
     * The function accepts following parameters:
     *  1. INTEGER n
     *  2. INTEGER_ARRAY routes
     */

     public static int connectingTowns(int n, List < int> routes)
    {
        int productOfRoads=1;
        for(int i=0; i < n-1;i++){           
            productOfRoads *= routes[i];         
            productOfRoads %= 1234567;
        }
        return productOfRoads;
    }

}

class Solution
{
    public static void Main(string[] args)
    {
        TextWriter textWriter = new StreamWriter(@System.Environment.GetEnvironmentVariable("OUTPUT_PATH"), true);

        int t = Convert.ToInt32(Console.ReadLine().Trim());

        for (int tItr = 0; tItr  <  t; tItr++)
        {
            int n = Convert.ToInt32(Console.ReadLine().Trim());

            List < int> routes = Console.ReadLine().TrimEnd().Split(' ').ToList().Select(routesTemp => Convert.ToInt32(routesTemp)).ToList();

            int result = Result.connectingTowns(n, routes);

            textWriter.WriteLine(result);
        }

        textWriter.Flush();
        textWriter.Close();
    }
}
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#4 Code Example with Java Programming

Code - Java Programming


import java.io.*;
import java.math.*;
import java.security.*;
import java.text.*;
import java.util.*;
import java.util.concurrent.*;
import java.util.function.*;
import java.util.regex.*;
import java.util.stream.*;
import static java.util.stream.Collectors.joining;
import static java.util.stream.Collectors.toList;

class Result {

    /*
     * Complete the 'connectingTowns' function below.
     *
     * The function is expected to return an INTEGER.
     * The function accepts following parameters:
     *  1. INTEGER n
     *  2. INTEGER_ARRAY routes
     */

       public static int connectingTowns(int n, List < Integer> routes) {
        long result=1;
        for(int i=0;i < n-1;i++){
            result*=routes.get(i);
            if(result>1234567)result%=1234567;
        }
        return (int)result;
        }

}

public class Solution {
    public static void main(String[] args) throws IOException {
        BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));
        BufferedWriter bufferedWriter = new BufferedWriter(new FileWriter(System.getenv("OUTPUT_PATH")));

        int t = Integer.parseInt(bufferedReader.readLine().trim());

        IntStream.range(0, t).forEach(tItr -> {
            try {
                int n = Integer.parseInt(bufferedReader.readLine().trim());

                List < Integer> routes = Stream.of(bufferedReader.readLine().replaceAll("\\s+$", "").split(" "))
                    .map(Integer::parseInt)
                    .collect(toList());

                int result = Result.connectingTowns(n, routes);

                bufferedWriter.write(String.valueOf(result));
                bufferedWriter.newLine();
            } catch (IOException ex) {
                throw new RuntimeException(ex);
            }
        });

        bufferedReader.close();
        bufferedWriter.close();
    }
}
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#5 Code Example with Javascript Programming

Code - Javascript Programming


'use strict';

const fs = require('fs');

process.stdin.resume();
process.stdin.setEncoding('utf-8');

let inputString = '';
let currentLine = 0;

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

process.stdin.on('end', function() {
    inputString = inputString.split('\n');

    main();
});

function readLine() {
    return inputString[currentLine++];
}

/*
 * Complete the 'connectingTowns' function below.
 *
 * The function is expected to return an INTEGER.
 * The function accepts following parameters:
 *  1. INTEGER n
 *  2. INTEGER_ARRAY routes
 */

function connectingTowns(n, routes) {
    return routes.reduce((acc, x) => x * acc % 1234567, 1) 
}

function main() {
    const ws = fs.createWriteStream(process.env.OUTPUT_PATH);

    const t = parseInt(readLine().trim(), 10);

    for (let tItr = 0; tItr  <  t; tItr++) {
        const n = parseInt(readLine().trim(), 10);

        const routes = readLine().replace(/\s+$/g, '').split(' ').map(routesTemp => parseInt(routesTemp, 10));

        const result = connectingTowns(n, routes);

        ws.write(result + '\n');
    }

    ws.end();
}
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#6 Code Example with Python Programming

Code - Python Programming


#!/bin/python3

import math
import os
import random
import re
import sys

#
# Complete the 'connectingTowns' function below.
#
# The function is expected to return an INTEGER.
# The function accepts following parameters:
#  1. INTEGER n
#  2. INTEGER_ARRAY routes
#

def connectingTowns(n, routes):
    # Write your code here
    r = 1
    for i in routes:
        r *= i
    return r%1234567

if __name__ == '__main__':
    fptr = open(os.environ['OUTPUT_PATH'], 'w')

    t = int(input().strip())

    for t_itr in range(t):
        n = int(input().strip())

        routes = list(map(int, input().rstrip().split()))

        result = connectingTowns(n, routes)

        fptr.write(str(result) + '\n')

    fptr.close()
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