Algorithm

Problem Name: Mathematics - Connecting Towns

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* 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;
}

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));

}
``````
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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)
{
for(int i=0; i < n-1;i++){
}
}

}

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

for (int tItr = 0; tItr  <  t; tItr++)
{

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 {
BufferedWriter bufferedWriter = new BufferedWriter(new FileWriter(System.getenv("OUTPUT_PATH")));

IntStream.range(0, t).forEach(tItr -> {
try {

.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);
}
});

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();
});

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);

for (let tItr = 0; tItr  <  t; tItr++) {

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):
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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